Sample records for natural composite materials

  1. Clues for biomimetics from natural composite materials

    PubMed Central

    Lapidot, Shaul; Meirovitch, Sigal; Sharon, Sigal; Heyman, Arnon; Kaplan, David L; Shoseyov, Oded

    2013-01-01

    Bio-inspired material systems are derived from different living organisms such as plants, arthropods, mammals and marine organisms. These biomaterial systems from nature are always present in the form of composites, with molecular-scale interactions optimized to direct functional features. With interest in replacing synthetic materials with natural materials due to biocompatibility, sustainability and green chemistry issues, it is important to understand the molecular structure and chemistry of the raw component materials to also learn from their natural engineering, interfaces and interactions leading to durable and highly functional material architectures. This review will focus on applications of biomaterials in single material forms, as well as biomimetic composites inspired by natural organizational features. Examples of different natural composite systems will be described, followed by implementation of the principles underlying their composite organization into artificial bio-inspired systems for materials with new functional features for future medicine. PMID:22994958

  2. New toughening concepts for ceramic composites from rigid natural materials.

    PubMed

    Mayer, George

    2011-07-01

    The mechanisms underlying the toughening in rigid natural composites exhibited by the concentric cylindrical composites of spicules of hexactinellid sponges, and by the nacre (brick-and-mortar) structure of mollusks such as Haliotis rufescens (red abalone), as well as the crossed-lamellar structure of Strombus gigas (queen conch) show commonalities in the manner in which toughening takes place. It is proposed that crack diversion, a new kind of crack bridging, resulting in retardation of delamination, creation of new surface areas, and other energy-dissipating mechanisms occur in both natural systems. However, these are generally different from the toughening mechanisms that are utilized for other classes of structural materials. Complementary to those mechanisms found in rigid natural ceramic/organic composites, special architectures and thin viscoelastic organic layers have been found to play controlling roles in energy dissipation in these structures. PMID:21565715

  3. Natural frequency and damping behavior of composite materials

    E-print Network

    Duggan, Matthew Brace

    1990-01-01

    . The goal is to be able to control and predict the vibration and damping of a composite structure in the design phase. 2. REVIEW OF LITERATURE Many models of composite plates have been proposed, but the effects of the stacking sequence, material system... to gain a data base for static and dynamic response of composite components. This project focuses on the vibration and damping characterization of composites in the presence of damage. The effects of selection of material system, size, stacking...

  4. Natural frequency and damping behavior of composite materials 

    E-print Network

    Duggan, Matthew Brace

    1990-01-01

    MODELS 6 12 23 5. RESULTS 25 5. 1 AS4/3501-6 Family 5. 2 IM7/E7T1-2 Family 5. 3 IM7/977-2 Family 5. 4 Numerical Comparison 25 39 50 58 6. CONCLUSIONS REFERENCES VITA 62 65 68 Vi LIST OF TABLES Table Test Matrix of Specimens. Properties... of AS4/3501-6, IM7/E7T1-2 and IM7/977-2. Natural Frequency and Damping of Undamaged AS4/3501-6 Plates. Natural Frequencies of Undamaged IM7/E7T1-2 Plates. Percent of Critical Damping for Undamaged IM&/E7T1-2 Plates. Natural Frequencies...

  5. Composite Materials

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Langley Research Center researchers invented an advanced polymer, a chemical compound formed by uniting many small molecules to create a complex molecule with different chemical properties. The material is a thermoplastic polyimide that resists solvents. Other polymers of this generic type are soluble in solvents, thus cannot be used where solvents are present. High Technology Services (HTS), Inc. licensed technology and is engaged in development and manufacture of high performance plastics, resins and composite materials. Techimer Materials Division is using technology for composite matrix resins that offer heat resistance and protection from radiation, electrical and chemical degradation. Applications of new polymer include molding resins, adhesives and matrix resins for fiber reinforced composites.

  6. Composite material

    Microsoft Academic Search

    Stacy A. Hutchens; Jonathan Woodward; Barbara R. Evans; Hugh M. ONeill

    2012-01-01

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft

  7. Composite material

    DOEpatents

    Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O'Neill, Hugh M. (Knoxville, TN)

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  8. Investigation of Polymer Resin/Fiber Compatibility in Natural Fiber Reinforced Composite Automotive Materials

    SciTech Connect

    Fifield, Leonard S.; Huang, Cheng; Simmons, Kevin L.

    2010-01-01

    Natural fibers represent a lower density and potentially lower cost alternative to glass fibers for reinforcement of polymers in automotive composites. The high specific modulus and strength of bast fibers make them an attractive option to replace glass not only in non-structural automotive components, but also in semi-structural and structural components. Significant barriers to insertion of bast fibers in the fiber reinforced automotive composite market include the high moisture uptake of this lignocellulosic material relative to glass and the weak inherent interface between natural fibers and automotive resins. This work seeks to improve the moisture uptake and resin interfacing properties of natural fibers through improved fundamental understanding of fiber physiochemical architecture and development of tailored fiber surface modification strategies.

  9. Composite Materials

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Composites are lighter and stronger than metals. Aramid fibers like Kevlar and Nomex were developed by DuPont Corporation and can be combined in a honeycomb structure which can give an airplane a light, tough structure. Composites can be molded into many aerodynamic shapes eliminating rivets and fasteners. Langley Research Center has tested composites for both aerospace and non-aerospace applications. They are also used in boat hulls, military shelters, etc.

  10. Local nature of the stress-strain state of a composite material subjected to frictional forces

    Microsoft Academic Search

    M. V. Kindrachuk; Yu. Ya. Dushek; M. V. Luchka

    1995-01-01

    The stress state arising in the near-surface layers of a material as a result of friction was investigated. The stress—strain state in a model composite material with included continuous high-modulus fibers was evaluated. The relationship between stress concentration, ratio of the matrix and inclusion mechanical properties, and the concentration and distribution of inclusions was determined. The regions of elevated stress

  11. Composite Materials Handbook

    NSDL National Science Digital Library

    From the US Army Research Laboratory, Materials Sciences Corporation, and University of Delaware Center for Composite Materials, the Composite Materials Handbook provides the "information and guidance necessary to design and fabricate end items from composite materials." Along with current information on the material properties of these composite materials, the handbook also includes data development and usage guidelines. The information has been divided into three areas: polymer, metal, and ceramic matrix composites. The Polymer Matrix Composites Handbook (three volumes including Guidelines for Characterization of Structural Materials; Material Properties; and Materials Usage, Design, and Analysis) and the Metal Matrix Composites Handbook (one volume, .pdf) are available here. The Ceramic Matrix Composites Handbook has yet to be completed. Users may also download Quick Composites Data in spreadsheet format.

  12. Mechanics of composite materials

    SciTech Connect

    Dvorak, G.J. (Inst. Center for Composite Materials and Structures, Rensselaer Polytechnic Inst. (US)); Laws, N. (Dept. of Mechanical Engineering, Univ. of Pittsburgh, PA (US))

    1988-01-01

    This book contains the following papers: crack growth resistance of TiB{sub 2} particulate/SiC matrix composite; constitutive relations of flexible composites under elastic deformation; determination of two kinds of composite plasticity: inclusions plastic vs. matrix plastic; 3-D analysis of transient interlaminar thermal stress of laminated composites; effect of seawater on the fracture toughness of pultruded rods; evaluation of new failure criterion for fibrous composite materials; and bridged cracks in fiber-reinforced composites.

  13. Composite material dosimeters

    DOEpatents

    Miller, Steven D. (Richland, WA)

    1996-01-01

    The present invention is a composite material containing a mix of dosimeter material powder and a polymer powder wherein the polymer is transparent to the photon emission of the dosimeter material powder. By mixing dosimeter material powder with polymer powder, less dosimeter material is needed compared to a monolithic dosimeter material chip. Interrogation is done with excitation by visible light.

  14. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1983-01-01

    Transverse properties of fiber constituents in composites, fatigue in composite materials, matrix dominated properties of high performance composites, numerical investigation of moisture effects, numerical investigation of the micromechanics of composite fracture, advanced analysis methods, compact lug design, and the RP-1 and RP-2 sailplanes projects are discussed.

  15. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1979-01-01

    Technology utilization of fiber reinforced composite materials is discussed in the areas of physical properties, and life prediction. Programs related to the Composite Aircraft Program are described in detail.

  16. Tough Composite Materials

    NASA Technical Reports Server (NTRS)

    Vosteen, L. F. (compiler); Johnson, N. J. (compiler); Teichman, L. A. (compiler)

    1984-01-01

    Papers and working group summaries are presented which address composite material behavior and performance improvement. Topic areas include composite fracture toughness and impact characterization, constituent properties and interrelationships, and matrix synthesis and characterization.

  17. Nano-composite materials

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

    2010-05-25

    Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

  18. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1979-01-01

    A multifaceted program is described in which aeronautical, mechanical, and materials engineers interact to develop composite aircraft structures. Topics covered include: (1) the design of an advanced composite elevator and a proposed spar and rib assembly; (2) optimizing fiber orientation in the vicinity of heavily loaded joints; (3) failure mechanisms and delamination; (4) the construction of an ultralight sailplane; (5) computer-aided design; finite element analysis programs, preprocessor development, and array preprocessor for SPAR; (6) advanced analysis methods for composite structures; (7) ultrasonic nondestructive testing; (8) physical properties of epoxy resins and composites; (9) fatigue in composite materials, and (10) transverse thermal expansion of carbon/epoxy composites.

  19. Acceleration and localization of subcritical crack growth in a natural composite material

    NASA Astrophysics Data System (ADS)

    Lennartz-Sassinek, S.; Main, I. G.; Zaiser, M.; Graham, C. C.

    2014-11-01

    Catastrophic failure of natural and engineered materials is often preceded by an acceleration and localization of damage that can be observed indirectly from acoustic emissions (AE) generated by the nucleation and growth of microcracks. In this paper we present a detailed investigation of the statistical properties and spatiotemporal characteristics of AE signals generated during triaxial compression of a sandstone sample. We demonstrate that the AE event amplitudes and interevent times are characterized by scaling distributions with shapes that remain invariant during most of the loading sequence. Localization of the AE activity on an incipient fault plane is associated with growth in AE rate in the form of a time-reversed Omori law with an exponent near 1. The experimental findings are interpreted using a model that assumes scale-invariant growth of the dominating crack or fault zone, consistent with the Dugdale-Barenblatt "process zone" model. We determine formal relationships between fault size, fault growth rate, and AE event rate, which are found to be consistent with the experimental observations. From these relations, we conclude that relatively slow growth of a subcritical fault may be associated with a significantly more rapid increase of the AE rate and that monitoring AE rate may therefore provide more reliable predictors of incipient failure than direct monitoring of the growing fault.

  20. Optical composite materials

    SciTech Connect

    Beecroft, L.L.; Ober, C.K.; Barber, D.B. [Cornell Univ., Ithaca, NY (United States)] [and others

    1995-12-31

    Optical quality composite materials can be useful for many applications. This work concerns optical quality composite films constructed from very small (<100 nm) particles of optically functional material embedded in a matrix of the same refractive index (RI). The particles impart their optical properties, while the matrix allows for processing of films. The initial optical composite studied contained Cr-forsterite (Cr-Mg{sub 2}SiO{sub 4}), a tunable solid state laser material in the attractive near-IR regime (1167-1345 nm). Small Cr-forsterite particles were synthesized by firing preceramic dispersion polymerization beads, and were embedded in unusually high RI polymeric matrix materials. Work to make optical amplification measurements is underway. This composite concept can be extended to other optically interesting materials.

  1. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, R.; Wiberley, S. E.

    1986-01-01

    Overall emphasis is on basic long-term research in the following categories: constituent materials, composite materials, generic structural elements, processing science technology; and maintaining long-term structural integrity. Research in basic composition, characteristics, and processing science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to present and future problems. Detailed descriptions of the progress achieved in the various component parts of this comprehensive program are presented.

  2. Electrically conductive composite material

    DOEpatents

    Clough, Roger L. (Albuquerque, NM); Sylwester, Alan P. (Albuquerque, NM)

    1989-01-01

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

  3. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1989-05-23

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  4. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1988-06-20

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  5. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1982-01-01

    The promise of filamentary composite materials, whose development may be considered as entering its second generation, continues to generate intense interest and applications activity. Fiber reinforced composite materials offer substantially improved performance and potentially lower costs for aerospace hardware. Much progress has been achieved since the initial developments in the mid 1960's. Rather limited applications to primary aircraft structure have been made, however, mainly in a material-substitution mode on military aircraft, except for a few experiments currently underway on large passenger airplanes in commercial operation. To fulfill the promise of composite materials completely requires a strong technology base. NASA and AFOSR recognize the present state of the art to be such that to fully exploit composites in sophisticated aerospace structures, the technology base must be improved. This, in turn, calls for expanding fundamental knowledge and the means by which it can be successfully applied in design and manufacture.

  6. Strength of composite materials

    Microsoft Academic Search

    F. F. Egorov; P. S. Kislyi; P. A. Verkhovodov

    1979-01-01

    1.A study was made of the strength of ZrN-Al2O3 composite materials produced by solid- and liquid-phase sintering in argon and nitrogen. It is shown that the strength of composites sintered in nitrogen is such less than that of composites sintered in argon, which is linked with the formation of new phases at boundaries between dissimilar phases and with a weakening

  7. Composite Material Switches

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid (Inventor)

    2001-01-01

    A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

  8. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1982-01-01

    Research in the basic composition, characteristics, and processng science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to problems. Detailed descriptions of the progress achieved in the various component parts of his program are presented.

  9. Mechanics of Composite Materials

    Microsoft Academic Search

    Robert M. Jones

    1999-01-01

    The mechanical behavior of composites is traditionally evaluated on both microscopic and macroscopic scale to take into account inhomogeneity. Micromechanics attempts to quantify the interactions of fiber and matrix (reinforcement and resin) on a microscopic scale on par with the diameter of a single fiber. Macromechanics treats composites as homogeneous materials, with mechanical properties representative of the laminate as a

  10. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, Robert G.; Wiberley, Stephen E.

    1987-01-01

    The development and application of composite materials to aerospace vehicle structures which began in the mid 1960's has now progressed to the point where what can be considered entire airframes are being designed and built using composites. Issues related to the fabrication of non-resin matrix composites and the micro, mezzo and macromechanics of thermoplastic and metal matrix composites are emphasized. Several research efforts are presented. They are entitled: (1) The effects of chemical vapor deposition and thermal treatments on the properties of pitch-based carbon fiber; (2) Inelastic deformation of metal matrix laminates; (3) Analysis of fatigue damage in fibrous MMC laminates; (4) Delamination fracture toughness in thermoplastic matrix composites; (5) Numerical investigation of the microhardness of composite fracture; and (6) General beam theory for composite structures.

  11. Resin composite restorative materials.

    PubMed

    Ilie, N; Hickel, R

    2011-06-01

    This paper surveys the most important developments in resin-based dental composites and focuses on the deficits (e.g. polymerization shrinkage) and strengths of the materials and their clinical implications. Moreover, differences between composite categories, such as hybrid, nanohybrid, microfilled, packable, ormocer-based, silorane-based, polyacid-modified composites (compomers) and flowable composites are highlighted, especially in view of their mechanical behaviour. In addition to the classical dimethacrylate-based composites, special attention is given to alternative monomers, such as siloranes, ormocers or high-molecular-weight dimethacrylate monomers (e.g. dimer acid-based dimethacrylates and tricyclodecane (TCD)-urethane), analysing their advantages, behaviour and abilities. Finally, the paper attempts to establish the needs and wishes of clinicians for further development of resin-based composites. PMID:21564116

  12. Aerogel/polymer composite materials

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  13. Composite electric contact materials

    NASA Astrophysics Data System (ADS)

    Senkara, J.; Kowalczyk, J.

    1985-12-01

    Two-phase composite materials, i.e., a high-melting component combined with a material exhibiting good electrical and thermal properties find a wide range of application for the manufacture of small- and medium-load relays and switches. Composite contacts can be used in air circuit-breakers (W-Ag, Ag-Ni), oil circuit-breakers (W-Cu, Mo-Cn), vacuum-type switches (W-CuSb, CuCr), and also switches operating in an atmosphere of SF sub 6 (W-Cu). Present-day trends aimed at increasing operating reliability and extending the service life of electrical equipment are finding their expression in efforts being made to modify the classical composites with a veiw to imparting new properties to them by suitably changing their composition and structure. These trends are also aimed at reducing the consumption of noble metals and of strategically important ones. Modern materials engineering and metallurgical technologies are being used, including isostatic sintering or explosive forming. Owing to the high activity of the constituents, all processes are conducted under high vacuum or in pure reducing atmospheres.

  14. Advanced composite materials and processes

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.

    1991-01-01

    Composites are generally defined as two or more individual materials, which, when combined into a single material system, results in improved physical and/or mechanical properties. The freedom of choice of the starting components for composites allows the generation of materials that can be specifically tailored to meet a variety of applications. Advanced composites are described as a combination of high strength fibers and high performance polymer matrix materials. These advanced materials are required to permit future aircraft and spacecraft to perform in extended environments. Advanced composite precursor materials, processes for conversion of these materials to structures, and selected applications for composites are reviewed.

  15. Natural Fiber or Glass Reinforced Polypropylene Composites?

    NASA Astrophysics Data System (ADS)

    Lorenzi, W.; Di Landro, L.; Casiraghi, A.; Pagano, M. R.

    2008-08-01

    Problems related to the recycle of conventional composite materials are becoming always more relevant for many industrial fields. Natural fiber composites (NFC) have recently gained much attention due to their low cost, environmental gains (eco-compatibility), easy disposal, reduction in volatile organic emissions, and their potential to compete with glass fiber composites (GFC). Interest in natural fibers is not only based over ecological aspects. NFC have good mechanical performances in relation to their low specific weight and low price. A characterization of mechanical properties, dynamic behavior, and moisture absorption is presented.

  16. NATURAL FIBER OR GLASS REINFORCED POLYPROPYLENE COMPOSITES?

    SciTech Connect

    Lorenzi, W.; Di Landro, L.; Casiraghi, A.; Pagano, M. R. [Dipartimento di Ingegneria Aerospaziale, Politecnico di Milano (Italy)

    2008-08-28

    Problems related to the recycle of conventional composite materials are becoming always more relevant for many industrial fields. Natural fiber composites (NFC) have recently gained much attention due to their low cost, environmental gains (eco-compatibility), easy disposal, reduction in volatile organic emissions, and their potential to compete with glass fiber composites (GFC). Interest in natural fibers is not only based over ecological aspects. NFC have good mechanical performances in relation to their low specific weight and low price. A characterization of mechanical properties, dynamic behavior, and moisture absorption is presented.

  17. Mechanics of composite materials

    Microsoft Academic Search

    G. J. Dvorak; N. Laws

    1988-01-01

    This book contains the following papers: crack growth resistance of TiBâ particulate\\/SiC matrix composite; constitutive relations of flexible composites under elastic deformation; determination of two kinds of composite plasticity: inclusions plastic vs. matrix plastic; 3-D analysis of transient interlaminar thermal stress of laminated composites; effect of seawater on the fracture toughness of pultruded rods; evaluation of new failure criterion for

  18. Composite materials: science and engineering

    SciTech Connect

    Chawla, K.K.

    1987-01-01

    The properties and applications of composite materials are examined in an introductory textbook for senior and graduate engineering students. Chapters are devoted to glass, B, C, organic, ceramic, and metallic fibers; polymer, ceramic, and metallic matrix materials; polymer-matrix composites; MMCs; ceramic-matrix composites; CFRPs; and multifilament superconducting composites. Consideration is given to the micromechanics of composites, macromechanical characteristics, strength, fracture, fatigue, and design problems. Diagrams, graphs, photographs, and tables of numerical data are included, and a set of problems is given for each chapter.

  19. Composite material heat pipe radiator

    Microsoft Academic Search

    Nelson J. Gernert; David B. Sarraf; Richard J. Guenther

    1996-01-01

    Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness

  20. Sitall-base composite materials

    Microsoft Academic Search

    I. I. Beloborodov; A. I. Yuga; N. D. Nazarenko; L. F. Kolesnichenko; N. I. Vlasko

    1976-01-01

    1.The feasibility is demonstrated of producing Sitall-base porous skeletons.2.Impregnation of a porous skeleton with a suspension of PTFE and graphite enables a composite material to be obtained possessing excellent antifriction properties.3.The presence of a metallic filler in such a composite material increases its load-carrying capacity.

  1. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The composite aircraft program component (CAPCOMP) is a graduate level project conducted in parallel with a composite structures program. The composite aircraft program glider (CAPGLIDE) is an undergraduate demonstration project which has as its objectives the design, fabrication, and testing of a foot launched ultralight glider using composite structures. The objective of the computer aided design (COMPAD) portion of the composites project is to provide computer tools for the analysis and design of composite structures. The major thrust of COMPAD is in the finite element area with effort directed at implementing finite element analysis capabilities and developing interactive graphics preprocessing and postprocessing capabilities. The criteria for selecting research projects to be conducted under the innovative and supporting research (INSURE) program are described.

  2. Composite Materials: Sticks and Glue

    NSDL National Science Digital Library

    Stoebe, Thomas G.

    This learning activity will provide a good example of "the effect on strength and stiffness of a material when it is manufactured as a composite." Popsicle sticks will be used to demonstrate the difference between singular materials and composite materials. Students will be able to see the added benefits of using composite materials. This activity would be suitable for elementary school through college level students, with each grade level gaining different educational benefits. The lesson should take from 5 to 20 minutes, depending on grade level. This document will serve as a framework for instructors and may be downloaded in PDF format.

  3. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, Robert G.; Wiberley, Stephen E.

    1988-01-01

    A decade long program to develop critical advanced composite technology in the areas of physical properties, structural concept and analysis, manufacturing, reliability, and life predictions is reviewed. Specific goals are discussed. The status of the chemical vapor deposition effects on carbon fiber properties; inelastic deformation of metal matrix laminates; fatigue damage in fibrous MMC laminates; delamination fracture toughness in thermoplastic matrix composites; and numerical analysis of composite micromechanical behavior are presented.

  4. Composite materials: A compilation

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Design, analysis and fabrication techniques for boron-aluminum composite-structure technology is presented and a new method of joining different laminated composites without mechanical fasteners is proposed. Also discussed is a low-cost procedure for rigidifying expanded honeycomb tubing and piping simulations. A brief note on patent information is added.

  5. Composite structural materials. [aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1980-01-01

    The use of filamentary composite materials in the design and construction of primary aircraft structures is considered with emphasis on efforts to develop advanced technology in the areas of physical properties, structural concepts and analysis, manufacturing, and reliability and life prediction. The redesign of a main spar/rib region on the Boeing 727 elevator near its actuator attachment point is discussed. A composite fabrication and test facility is described as well as the use of minicomputers for computer aided design. Other topics covered include (1) advanced structural analysis methids for composites; (2) ultrasonic nondestructive testing of composite structures; (3) optimum combination of hardeners in the cure of epoxy; (4) fatigue in composite materials; (5) resin matrix characterization and properties; (6) postbuckling analysis of curved laminate composite panels; and (7) acoustic emission testing of composite tensile specimens.

  6. Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials

    Microsoft Academic Search

    P K Hansma; P J Turner; R S Ruoff

    2007-01-01

    From our investigations of natural composite materials such as abalone shell and bone we have learned the following. (1) Nature is frugal with resources: it uses just a few percent glue, by weight, to glue together composite materials. (2)Nature does not avoid voids. (3) Nature makes optimized glues with sacrificial bonds and hidden length. We discuss how optimized adhesives combined

  7. Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials

    Microsoft Academic Search

    P. K. Hansma; P. J. Turner; R. S. Ruoff

    2007-01-01

    From our investigations of natural composite materials such as abalone shell and bone we have learned the following. (1) Nature is frugal with resources: it uses just a few per cent glue, by weight, to glue together composite materials. (2) Nature does not avoid voids. (3) Nature makes optimized glues with sacrificial bonds and hidden length. We discuss how optimized

  8. Natural ageing of EPDM composite insulators

    Microsoft Academic Search

    A. E. Vlastos; E. Sherif

    1990-01-01

    Long-rod composite insulators, with weather sheds (sheds) made of ethylene propylene rubbers (EPDM), were exposed for many years to HVAC and HVDC under realistic conditions and natural pollution. The change of their properties with time and their aging was studied. The results show that the insulator shed material undergoes a slow degradation process and loses successively its water repelling properties

  9. Composite structural materials. [aircraft applications

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The development of composite materials for aircraft applications is addressed with specific consideration of physical properties, structural concepts and analysis, manufacturing, reliability, and life prediction. The design and flight testing of composite ultralight gliders is documented. Advances in computer aided design and methods for nondestructive testing are also discussed.

  10. Recycling of composite materials

    Microsoft Academic Search

    M. Buggy; L. Farragher; W. Madden

    1995-01-01

    An economic survey of composite manufacturing was carried out to help to identify suitable fibre\\/resin systems for recycling trials. Three separate recycling strategies were also adopted. The first of these was the re-use of in-process polyester\\/glass prepreg offcuts, which were quantified and then reprocessed using a simple pressing technique. Three different panel types were pressed and subjected to comparative physical

  11. Ski Technology And Composite Materials

    NSDL National Science Digital Library

    2010-01-01

    The following resource is from Lessonopoly, which has created student activities and lesson plans to support the video series, Science of the Olympic Winter Games, created by NBC Learn and the National Science Foundation. Featuring exclusive footage from NBC Sports and contributions from Olympic athletes and NSF scientists, the series will help teach your students valuable scientific concepts. Students will learn the basic engineering issues related to ski design. They will learn about composite materials and polymer materials. Also, students will create and test a composite material.

  12. Nanophase and Composite Optical Materials

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This talk will focus on accomplishments, current developments, and future directions of our work on composite optical materials for microgravity science and space exploration. This research spans the order parameter from quasi-fractal structures such as sol-gels and other aggregated or porous media, to statistically random cluster media such as metal colloids, to highly ordered materials such as layered media and photonic bandgap materials. The common focus is on flexible materials that can be used to produce composite or artificial materials with superior optical properties that could not be achieved with homogeneous materials. Applications of this work to NASA exploration goals such as terraforming, biosensors, solar sails, solar cells, and vehicle health monitoring, will be discussed.

  13. High-temperature composite materials

    Microsoft Academic Search

    Yu. L. Pilipovskii; L. G. Vishnevskii; T. V. Grudina; L. N. Pereselentseva

    1996-01-01

    In the second half of the 60's the development of composite materials extremely necessary in service under conditions of intense short-term action of high-temperature gas flows which bear a significant quantity of condensed phase was started in the Institute of Material Science under the leadership of I. N. Frantsevich and then D. M. Karpinos. These materials must possess high erosion-

  14. Composite materials for space applications

    NASA Technical Reports Server (NTRS)

    Rawal, Suraj P.; Misra, Mohan S.; Wendt, Robert G.

    1990-01-01

    The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values.

  15. Fiber composite materials technology development

    SciTech Connect

    Chiao, T.T.

    1980-10-23

    The FY1980 technical accomplishments from the Lawrence Livermore National laboratory (LLNL) for the Fiber Composite Materials Technology Development Task fo the MEST project are summarized. The task is divided into three areas: Engineering data base for flywheel design (Washington University will report this part separately), new materials evaluation, and time-dependent behavior of Kevlar composite strands. An epoxy matrix was formulated which can be used in composites for 120/sup 0/C service with good processing and mechanical properties. Preliminary results on the time-dependent properties of the Kevlar 49/epoxy strands indicate: Fatigue loading, as compared to sustained loading, drastically reduces the lifetime of a Kevlar composie; the more the number of on-off load cycles, the less the lifetime; and dynamic fatigue of the Kevlar composite can not be predicted by current damage theories such as Miner's Rule.

  16. Fracture problems in composite materials

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1972-01-01

    A series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels. The topics discussed include a crack in layered composites, a crack terminating at and going through a bi-material interface, a penny-shaped crack in a filament-reinforced elastic matrix, and inclusion problems in bonded materials.

  17. Composite material impregnation unit

    NASA Technical Reports Server (NTRS)

    Wilkinson, S. P.; Marchello, J. M.; Johnston, N. J.

    1993-01-01

    This memorandum presents an introduction to the NASA multi-purpose prepregging unit which is now installed and fully operational at the Langley Research Center in the Polymeric Materials Branch. A description of the various impregnation methods that are available to the prepregger are presented. Machine operating details and protocol are provided for its various modes of operation. These include, where appropriate, the related equations for predicting the desired prepreg specifications. Also, as the prepregger is modular in its construction, each individual section is described and discussed. Safety concerns are an important factor and a chapter has been included that highlights the major safety features. Initial experiences and observations for fiber impregnation are described. These first observations have given great insight into the areas of future work that need to be addressed. Future memorandums will focus on these individual processes and their related problems.

  18. Impact response of composite materials

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Srinivasan, K.

    1991-01-01

    Composite materials composed of carbon fibers and resin matrices offer great promise in reducing the weight of aerospace structures. However they remain extremely vulnerable to out of plane impact loads, which lead to severe losses in strength and stiffness. The results of an experimental program, undertaken to investigate the low velocity impact damage tolerance of composite materials is presented. The objectives were to identify key neat resin/composite properties that lead to enhancement of composite impact damage tolerance and to find a small scale test that predicts compression after impact properties of panels. Five materials were selected for evaluation. These systems represented different classes of material behavior such as brittle epoxy, modified epoxies, and amorphous and semicrystalling thermoplastics. The influence of fiber properties on the impact performance was also studied in one material, i.e., in polyether ether ketone (PEEK). Several 24 and 48 ply quasi-isotropic and 24 ply orthotropic laminates were examined using an instrumented drop weight impactor. Correlations with post impact compression behavior were made.

  19. Mechanical performance of woodfibre–waste plastic composite materials

    Microsoft Academic Search

    Krishnan Jayaraman; Debes Bhattacharyya

    2004-01-01

    Plastic products used for packaging are often discarded after a single use resulting in an inexhaustible supply of waste polymeric materials. The stiffness and strength of polymeric materials have been known to improve with the addition of lignocellulosic fibres available in abundance in nature. Hence, composite materials containing natural fibres and waste plastics would result in the reduction of solid

  20. Joining of polymer composite materials

    SciTech Connect

    Magness, F.H.

    1990-11-01

    Under ideal conditions load bearing structures would be designed without joints, thus eliminating a source of added weight, complexity and weakness. In reality the need for accessibility, repair, and inspectability, added to the size limitations imposed by the manufacturing process and transportation/assembly requirements mean that some minimum number of joints will be required in most structures. The designer generally has two methods for joining fiber composite materials, adhesive bonding and mechanical fastening. As the use of thermoplastic materials increases, a third joining technique -- welding -- will become more common. It is the purpose of this document to provide a review of the available sources pertinent to the design of joints in fiber composites. The primary emphasis is given to adhesive bonding and mechanical fastening with information coming from documentary sources as old as 1961 and as recent as 1989. A third, shorter section on composite welding is included in order to provide a relatively comprehensive treatment of the subject.

  1. Hugoniot Analysis of Composite Materials

    Microsoft Academic Search

    S. K. Garg; J. W. Kirsch

    1971-01-01

    A generalized set of conservation equations (i.e., the Hugoniot relations) across a disturbance propagating through a composite material with a steady velocity are derived within the framework of the Theory of Inter acting Continua. By providing a rational basis for comparison, the analysis clarifies the differences between the earlier studies in this field. In addition, the present development of the

  2. ADVANCED COMPOSITE MATERIALS HEAT BRIDGES

    Microsoft Academic Search

    A. B. Shopen; V. A. Golovanevskiy; O. A. Kivirenko

    Understanding heat transfer properties of advanced composite materials (CM) structures is gaining increasing importance in industries such as medicine and cryogenics, aerospace and electronics where structures made from advanced CM are being used as heat bridges. The main goal in such applications of advanced CM structures is achieving maximum load bearing capacity while maintaining heat transfer rate at a predetermined

  3. Durability of polymer composite materials

    Microsoft Academic Search

    Liu Liu

    2006-01-01

    The purpose of this research is to examine structural durability of advanced composite materials under critical loading conditions, e.g., combined thermal and mechanical loading and shear fatigue loading. A thermal buckling model of a burnt column, either axially restrained or under an axial applied force was developed. It was predicted that for a column exposed to the high heat flux

  4. Estimating the molecular composition of a diverse range of natural organic materials from solid-state 13 C NMR and elemental analyses

    Microsoft Academic Search

    Paul N. Nelson; Jeffrey A. Baldock

    2005-01-01

    Most techniques for determining the chemical nature of natural organic matter in soil, sediment and water require prior extraction or concentration steps that are not quantitative and that create artifacts. 13C nuclear magnetic resonance (NMR) analysis can avoid these problems, but it gives little information at the scale of molecules. Here we show that the molecular composition of a diverse

  5. Elementary damping properties in braided composite materials

    NASA Astrophysics Data System (ADS)

    Dion, Bernard L.; Sadler, Robert; Silverberg, Larry

    1994-05-01

    This paper investigates the damping level trends of three-dimensionally braided composites as a function of matrix material, fiber-matrix interface, fiber braid angle, fiber volume, and axial fiber tow size. With knowledge of such trends, designers may increase the structural damping in a 3-D braided composite component, thereby reducing component vibration, shock response, and fatigue. The logarithmic decrements of the fundamental mode response of cantilevered, 3-D braided composite beam specimens were calculated for comparison. Although the logarithmic decrements of two specimens, differing only in their matrix materials (Tactix 123 and Epon 828), were essentially identical, both were considerably larger than that for steel. The value for the decrement of these two composite specimens' response was taken as a reference. Altering the nature of the fiber-matrix interface by lubricating the fibers before specimen consolidation greatly increased the damping relative to the baseline. Trends of increasing damping were measured with both increasing fiber braid angle and fiber volume. Finally, increasing levels of damping are reported for decreases in axial fiber tow size. Explanations for these trends, based on the possible microscopic and macroscopic nature of the braided composites, are offered.

  6. New wear resistant composite material

    SciTech Connect

    Angers, R.; Champagne, B.; Fiset, M.; Chollet, P.

    1983-01-01

    A composite material consisting of WC-Co particles in a steel matrix was fabricated by sintering mixtures of WC-Co particles and a steel powder and infiltrating the sintered pieces with a copper alloy. Its wear resistance and mechanical properties were studied as a function of the content in WC-Co particles and other characteristics of the composite material microstructure. Infiltration provided a simple means to obtain a strong cohesion between WC-Co particles and the steel matrix. An effective matrix protection against wear is obtained with relatively low additions of particles especially with a silica abrasive which is soft with respect to cemented carbide. The experimental results show that this material has good mechanical properties and wear resistance. Depending upon abrasion resistance, wear losses are reduced up to 10 times by a 30 vol% addition of cemented carbide particles.

  7. Computational modeling of composite material fires

    Microsoft Academic Search

    Alexander L. Brown; Kenneth L. Erickson; Joshua Allen Hubbard; Amanda B. Dodd

    2010-01-01

    Composite materials behave differently from conventional fuel sources and have the potential to smolder and burn for extended time periods. As the amount of composite materials on modern aircraft continues to increase, understanding the response of composites in fire environments becomes increasingly important. An effort is ongoing to enhance the capability to simulate composite material response in fires including the

  8. Fracture problems in composite materials.

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1972-01-01

    In this paper a series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels.

  9. Damage detection in composite materials using frequency response methods

    Microsoft Academic Search

    Seth S. Kessler; S. Mark Spearing; Mauro J. Atalla; Carlos E. S. Cesnik; Constantinos Soutis

    2002-01-01

    Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for the in situ detection of damage in composite materials. The experimental results are presented for the application of modal analysis techniques applied to graphite\\/epoxy specimens containing representative damage modes. Changes in natural frequencies

  10. Aeroelastic tailoring of composite materials 

    E-print Network

    Rogers, Jesse Byron

    1979-01-01

    LIST OF FIGURES IiiTRODUCTI ON ST!!UCTURAL RESPONSE Deformation of Uniformly Stressed Isotropic and Anisotropic Plates Characterization of Composite Laminates . Effect of Material Parameters APPLICATIONS Aircraft Propellers Ship Propell rs... com- pliances with laminate rotation 39 15 Variation of (A) extensional ard (8) bending compliances with 0' ply rotation . . . . . . . . . . . . . . . . 40 16 Incremental aerodynamic forces on a typical blade element 43 17 Propeller velocity...

  11. Improved Silica Aerogel Composite Materials

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

    2008-01-01

    A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

  12. Properties of composite materials for cryogenic applications

    Microsoft Academic Search

    J. B Schutz

    1998-01-01

    Composite materials are used in a wide variety of cryogenic applications because of their unique and highly tailorable properties. These cryogenic applications of composites may be, for the sake of discussion, classified as support structures, vessels, or electrical insulation. Examples of these applications are presented, with a brief discussion of the critical material properties associated with each application. Composite material

  13. ULTRASONIC CHARACTERIZATION OF ADVANCED COMPOSITE MATERIALS

    Microsoft Academic Search

    B. Boro Djordjevic

    With increased use of composite materials in critical structural applications it is more important than ever to independently assure structural integrity. Complexity of the advanced composite materials including layered and bonded structures represents challenges in developing optimized ultrasonic tests. Traditional ultrasonic NDT methods are inappropriate and often misleading when applied to anisotropic and nonhomogeneous composite materials. In advanced technology applications

  14. Nonintrusive interfacial characterization of advanced composite materials

    Microsoft Academic Search

    Renee M. Kent

    1995-01-01

    It is well known that the fiber matrix interface plays the dominant role in the mechanical behavior of advanced composite materials. Engineering and control of the interface is paramount to producing the properties for desired mechanical performance of the ultimate composite structure. This is particularly critical for advanced composites (metal matrix composites, ceramic matrix composites) which are currently being investigated

  15. Self-healing polymer composites: mimicking nature to enhance performance

    Microsoft Academic Search

    R S Trask; H R Williams; I P Bond

    2007-01-01

    Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies

  16. Composite materials for thermal energy storage

    DOEpatents

    Benson, David K. (Golden, CO); Burrows, Richard W. (Conifer, CO); Shinton, Yvonne D. (Northglenn, CO)

    1986-01-01

    The present invention discloses composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These phase change materials do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions, such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  17. GROWING ALTERNATIVE SUSTAINABLE BUILDINGS: BIO-COMPOSITE PRODUCTS FROM NATURAL FIBER, BIODEGRADABLE AND RECYCLABLE POLYMER MATERIALS FOR LOAD-BEARING CONSTRUCTION COMPONENTS

    EPA Science Inventory

    The project is an integrative educational and research project that will revolutionize design and construction methods towards more sustainable buildings. The project will develop and test new product design concepts using bio-composite materials in load-bearing and fa&cced...

  18. Composite material heat pipe radiator

    NASA Astrophysics Data System (ADS)

    Gernert, Nelson J.; Sarraf, David B.; Guenther, Richard J.; Hurlbert/, Kathryn Miller

    1996-03-01

    Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness (0.076 mm). The thin liner transitioned to heavier-walled ends which allowed the tubing to be sealed using conventional welding. More specifically, the heat pipe was 1.14 m long, 24 mm in diameter and had a mass of 0.165 kg. Water was the working fluid. The heat pipe was tested in a Thermacore thermal vacuum chamber under hot and cold wall operating conditions. The heat load dissipated ranged from 10 to 60 watts. Heat pipe operating temperatures varied from 278 K to 403 K. After testing, the heat pipe was delivered to NASA JSC where future thermal vacuum chamber tests are planned.

  19. Estimating Weibull parameters for composite materials.

    NASA Technical Reports Server (NTRS)

    Robinson, E. Y.

    1972-01-01

    This paper deals with the statistical analysis of strength and fracture of materials in general, with application to fiber composites. The 'weakest link' model is considered in a fairly general form, and the resulting equations are demonstrated by using a Weibull distribution for flaws. This distribution appears naturally in a variety of problems, and therefore additional attention is devoted to analysis and statistical estimation connected with this distribution. Special working charts are included to facilitate interpretation of observed data and estimation of parameters. Implications of the size effect are considered for various kinds of flaw distributions. The paper describes failure and damage in a fiber-reinforced systems.

  20. Composite materials for thermal energy storage

    DOEpatents

    Benson, D.K.; Burrows, R.W.; Shinton, Y.D.

    1985-01-04

    A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  1. Self-healing polymer composites: mimicking nature to enhance performance.

    PubMed

    Trask, R S; Williams, H R; Bond, I P

    2007-03-01

    Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies currently being developed for fibre reinforced polymeric composite materials, most of which are bioinspired, inspired by observation of nature. The most recent self-healing work has attempted to mimic natural healing through the study of mammalian blood clotting and the design of vascular networks found in biological systems. A perspective on current and future self-healing approaches using this biomimetic technique is offered. The intention is to stimulate debate outside the engineering community and reinforce the importance of a multidisciplinary approach in this exciting field. PMID:17671320

  2. Polyolefin composites containing a phase change material

    DOEpatents

    Salyer, Ival O. (Dayton, OH)

    1991-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein, said polyolefin being thermally form stable; the composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

  3. Explorations in the application of nanotechnology to improve the mechanical properties of composite materials

    Microsoft Academic Search

    Cheng Yang

    2007-01-01

    This thesis presents the research achievements on the design, preparation, characterization, and analysis of a series of composite materials. By studying the interface interaction of the composite materials using nanotechnology, we developed composite materials that achieve satisfactory mechanical properties in two classes of materials. Durable press (DP) natural textiles are important consumer products usually achieved by erosslinking the molecules in

  4. Vibrational Damping of Composite Materials

    E-print Network

    Biggerstaff, Janet M.

    2006-01-01

    polymeric composites composed of fibers (graphite, Kevlar,by Cape Composites, had intermediate modulus graphite fibersFiber and Resin on the Vibration Damping of Composites Reinforced wit Fiberglass, Graphite, and

  5. Composite material and method of making

    DOEpatents

    Fryxell, Glen E.; Samuels, William D.; Simmons, Kevin L.

    2004-04-20

    The composite material and methods of making the present invention rely upon a fully dense monolayer of molecules attached to an oxygenated surface at one end, and an organic terminal group at the other end, which is in turn bonded to a polymer. Thus, the composite material is a second material chemically bonded to a polymer with fully dense monolayer there between.

  6. Nonlinear Dynamic Properties of Layered Composite Materials

    SciTech Connect

    Andrianov, Igor V.; Topol, Heiko; Weichert, Dieter [Institute of General Mechanics, RWTH Aachen University, Termplergraben 64, Aachen, D-52062 (Germany); Danishevs'kyy, Vladyslav V. [Prydniprovs'ka State Academy of Civil Engineering and Architecture, Dnipropetrovs'k, Chernishevs'kogo 24a, UA-49600 (Ukraine)

    2010-09-30

    We present an application of the asymptotic homogenization method to study wave propagation in a one-dimensional composite material consisting of a matrix material and coated inclusions. Physical nonlinearity is taken into account by considering the composite's components as a Murnaghan material, structural nonlinearity is caused by the bonding condition between the components.

  7. Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials

    NASA Astrophysics Data System (ADS)

    Hansma, P. K.; Turner, P. J.; Ruoff, R. S.

    2007-01-01

    From our investigations of natural composite materials such as abalone shell and bone we have learned the following. (1) Nature is frugal with resources: it uses just a few per cent glue, by weight, to glue together composite materials. (2) Nature does not avoid voids. (3) Nature makes optimized glues with sacrificial bonds and hidden length. We discuss how optimized adhesives combined with high specific stiffness/strength structures such as carbon nanotubes or graphene sheets could yield remarkably strong, lightweight, and damage-resistant materials.

  8. Predictive rendering of composite materials: a multi-scale approach

    NASA Astrophysics Data System (ADS)

    Muller, T.; Callet, P.; da Graça, F.; Paljic, A.; Porral, P.; Hoarau, R.

    2015-03-01

    Predictive rendering of material appearance means going deep into the understanding of the physical interaction between light and matter and how these interactions are perceived by the human brain. In this paper we describe our approach to predict the appearance of composite materials by relying on the multi-scale nature of the involved phenomena. Using recent works on physical modeling of complex materials, we show how to predict the aspect of a composite material based on its composition and its morphology. Specifically, we focus on the materials whose morphological structures are defined at several embedded scales. We rely on the assumption that when the inclusions in a composite material are smaller than the considered wavelength, the optical constants of the corresponding effective media can be computed by a homogenization process (or analytically for special cases) to be used into the Fresnel formulas.

  9. DAMAGE DETECTION IN COMPOSITE MATERIALS USING FREQUENCY RESPONSE METHODS

    Microsoft Academic Search

    Seth S. Kessler; S. Mark Spearing; Mauro J. Atalla; Carlos E. S. Cesnik; Constantinos Soutis

    2001-01-01

    Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for the in-situ detection of damage in composite materials. The experimental results are presented for the application of modal analysis techniques applied to graphite\\/epox y specimens containing representative damage modes. Changes in natural frequencies

  10. Improved Damage Resistant Composite Materials Incorporating Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Paine, Jeffrey S. N.; Rogers, Craig A.

    1996-01-01

    Metallic shape memory alloys (SMA) such as nitinol have unique shape recovery behavior and mechanical properties associated with a material phase change that have been used in a variety of sensing and actuation applications. Recent studies have shown that integrating nitinol-SMA actuators into composite materials increases the composite material's functionality. Hybrid composites of conventional graphite/epoxy or glass/epoxy and nitinol-SMA elements can perform functions in applications where monolithic composites perform inadequately. One such application is the use of hybrid composites to function both in load bearing and armor capacities. While monolithic composites with high strength-to-weight ratios function efficiently as loadbearing structures, because of their brittle nature, impact loading can cause significant catastrophic damage. Initial composite failure modes such as delamination and matrix cracking dissipate some impact energy, but when stress exceeds the composite's ultimate strength, fiber fracture and material perforation become dominant. One of the few methods that has been developed to reduce material perforation is hybridizing polymer matrix composites with tough kevlar or high modulus polyethynylene plies. The tough fibers increase the impact resistance and the stiffer and stronger graphite fibers carry the majority of the load. Similarly, by adding nitinol-SMA elements that absorb impact energy through the stress-induced martensitic phase transformation, the composites' impact perforation resistance can be greatly enhanced. The results of drop-weight and high velocity gas-gun impact testing of various composite materials will be presented. The results demonstrate that hybridizing composites with nitinol-SMA elements significantly increases perforation resistance compared to other traditional toughening elements. Inspection of the composite specimens at various stages of perforation by optical microscope illustrates the mechanisms by which perforation is initiated. Results suggest that the out-of-plane transverse shear properties of the composite and nitinol elements have a significant effect on the perforation resistance. Applications that can utilize the hybrid composites effectively will also be presented with the experimental studies.

  11. Morphology and microstructure of composite materials

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Srinivansan, K.

    1991-01-01

    Lightweight continuous carbon fiber based polymeric composites are currently enjoying increasing acceptance as structural materials capable of replacing metals and alloys in load bearing applications. As with most new materials, these composites are undergoing trials with several competing processing techniques aimed at cost effectively producing void free consolidations with good mechanical properties. As metallic materials have been in use for several centuries, a considerable database exists on their morphology - microstructure; and the interrelationships between structure and properties have been well documented. Numerous studies on composites have established the crucial relationship between microstructure - morphology and properties. The various microstructural and morphological features of composite materials, particularly those accompanying different processing routes, are documented.

  12. Composite structural materials. [fiber reinforced composites for aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

    1981-01-01

    Physical properties of fiber reinforced composites; structural concepts and analysis; manufacturing; reliability; and life prediction are subjects of research conducted to determine the long term integrity of composite aircraft structures under conditions pertinent to service use. Progress is reported in (1) characterizing homogeneity in composite materials; (2) developing methods for analyzing composite materials; (3) studying fatigue in composite materials; (4) determining the temperature and moisture effects on the mechanical properties of laminates; (5) numerically analyzing moisture effects; (6) numerically analyzing the micromechanics of composite fracture; (7) constructing the 727 elevator attachment rib; (8) developing the L-1011 engine drag strut (CAPCOMP 2 program); (9) analyzing mechanical joints in composites; (10) developing computer software; and (11) processing science and technology, with emphasis on the sailplane project.

  13. NASA technology utilization survey on composite materials

    NASA Technical Reports Server (NTRS)

    Leeds, M. A.; Schwartz, S.; Holm, G. J.; Krainess, A. M.; Wykes, D. M.; Delzell, M. T.; Veazie, W. H., Jr.

    1972-01-01

    NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given.

  14. Wave propagation and impact in composite materials

    NASA Technical Reports Server (NTRS)

    Moon, F. C.

    1975-01-01

    Anisotropic waves in composites are considered, taking into account wave speeds, wave surfaces, flexural waves in orthotropic plates, surface waves, edge waves in plates, and waves in coupled composite plates. Aspects of dispersion in composites are discussed, giving attention to pulse propagation and dispersion, dispersion in rods and plates, dispersion in a layered composite, combined material and structural dispersion, continuum theories for composites, and variational methods for periodic composites. The characteristics of attenuation and scattering processes are examined and a description is given of shock waves and impact problems in composites. A number of experiments are also reported.

  15. Composite materials and method of making

    DOEpatents

    Simmons, Kevin L [Kennewick, WA; Wood, Geoffrey M [North Saanich, CA

    2011-05-17

    A method for forming improved composite materials using a thermosetting polyester urethane hybrid resin, a closed cavity mold having an internal heat transfer mechanism used in this method, and the composite materials formed by this method having a hybrid of a carbon fiber layer and a fiberglass layer.

  16. Stress distribution in antifriction composite materials

    Microsoft Academic Search

    L. V. Zabolotnyi

    1979-01-01

    The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high

  17. Advanced composite materials: a strong growth industry

    Microsoft Academic Search

    Lees

    1987-01-01

    Advanced composites represent a material form that will see significant growth in structural applications. The authors notes that Du Pont sees a broad opportunity for these materials and proceeds to review reasons for the company's optimism as well as their approach to this technology. Substitution of composites for metals is shown graphically since 1960 and projected to 2025. Price reductions

  18. Composite Dielectric Materials for Electrical Switching

    SciTech Connect

    Modine, F.A.

    1999-04-25

    Composites that consist of a dielectric host containing a particulate conductor as a second phase are of interest for electrical switching applications. Such composites are "smart" materials that can function as either voltage or current limiters, and the difference in fimction depends largely upon whether the dielectric is filled to below or above the percolation threshold. It also is possible to combine current and voltage limiting in a single composite to make a "super-smart" material.

  19. Advanced composites: Environmental effects on selected resin matrix materials

    NASA Technical Reports Server (NTRS)

    Welhart, E. K.

    1976-01-01

    The effects that expected space flight environment has upon the mechanical properties of epoxy and polyimide matrix composites were analyzed. Environmental phenomena covered water immersion, high temperature aging, humidity, lightning strike, galvanic action, electromagnetic interference, thermal shock, rain and sand erosion, and thermal/vacuum outgassing. The technology state-of-the-art for graphite and boron reinforced epoxy and polyimide matrix materials is summarized to determine the relative merit of using composites in the space shuttle program. Resin matrix composites generally are affected to some degree by natural environmental phenomena with polyimide resin matrix materials less affected than epoxies.

  20. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

    New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

  1. Natural materials for carbon capture.

    SciTech Connect

    Myshakin, Evgeniy M. (National Energy Technology Laboratory, Pittsburgh, PA); Romanov, Vyacheslav N. (National Energy Technology Laboratory, Pittsburgh, PA); Cygan, Randall Timothy

    2010-11-01

    Naturally occurring clay minerals provide a distinctive material for carbon capture and carbon dioxide sequestration. Swelling clay minerals, such as the smectite variety, possess an aluminosilicate structure that is controlled by low-charge layers that readily expand to accommodate water molecules and, potentially, carbon dioxide. Recent experimental studies have demonstrated the efficacy of intercalating carbon dioxide in the interlayer of layered clays but little is known about the molecular mechanisms of the process and the extent of carbon capture as a function of clay charge and structure. A series of molecular dynamics simulations and vibrational analyses have been completed to assess the molecular interactions associated with incorporation of CO2 in the interlayer of montmorillonite clay and to help validate the models with experimental observation.

  2. Flame-retardant composite materials

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1991-01-01

    The properties of eight different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: VPSP/BMI, a blend of vinylpolystyryl pyridine and bismaleimide; BMI, a bismaleimide; and phenolic and PSP, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that VPSP/BMI with the graphite tape was the optimum design giving the lowest heat release rate.

  3. Machining of Sitall-base composite materials

    Microsoft Academic Search

    L. F. Kolesnichenko; N. D. Nazarenko; A. I. Yuga; N. I. Vlasko; F. D. Ivashov; L. L. Sukhikh; G. A. Sedlyar

    1976-01-01

    Investigations have shown that in the grinding of Sitall with an abrasive tool removal of material is slow owing to poor heat transfer from the cutting zone and the high hardness of Sitall. By contrast, use of diamond disks in the grinding of Sitall-base composite materials enables high rates of material removal to be attained with a good surface finish.

  4. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  5. Oxygen Compatibility Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Engel, Carl D.; Watkins, Casey N.

    2006-01-01

    Composite materials offer significant weight-saving potential for aerospace applications in propellant and oxidizer tanks. This application for oxygen tanks presents the challenge of being oxygen compatible in addition to complying with the other required material characteristics. This effort reports on the testing procedures and data obtained in examining and selecting potential composite materials for oxygen tank usage. Impact testing of composites has shown that most of these materials initiate a combustion event when impacted at 72 ft-lbf in the presence of liquid oxygen, though testing has also shown substantial variability in reaction sensitivities to impact. Data for screening of 14 potential composites using the Bruceton method is given herein and shows that the 50-percent reaction frequencies range from 17 to 67 ft-lbf. The pressure and temperature rises for several composite materials were recorded to compare the energy releases as functions of the combustion reactions with their respective reaction probabilities. The test data presented are primarily for a test pressure of 300 psia in liquid oxygen. The impact screening process is compared with oxygen index and autogenous ignition test data for both the composite and the basic resin. The usefulness of these supplemental tests in helping select the most oxygen compatible materials is explored. The propensity for mechanical impact ignition of the composite compared with the resin alone is also examined. Since an ignition-free composite material at the peak impact energy of 72 ft-lbf has not been identified, composite reactivity must be characterized over the impact energy level and operating pressure ranges to provide data for hazard analyses in selecting the best potential material for liquid tank usage.

  6. The nature of cometary materials

    NASA Technical Reports Server (NTRS)

    Stephens, James

    1989-01-01

    Because cometary surfaces are likely to be far colder and of a different composition than planetary surfaces, there are some new considerations that must be examined in regards to placing instrumented packages or sample return devices on their surfaces. The qualitative analysis of the problem of attaching hardware to a comet and not being ejected back into space can be divided into two parts. The first problem is to pierce the mantle and obtain access to the icy core. Drilling through the mantle requires that the drilling forces be reacted. Reacting such forces probably requires attachment to the icy core below. Therefore, some kinetic impact piercing device is likely to be required as the first act of attachment. The second problem for a piercing device to overcome is the force produced by the impact kinetic energy that tries to eject the piercing device back into space. The mantle and icy core can absorb some of the impact kinetic energy in the form of fracture formation and friction energy. The energy that is not absorbed in these two ways is stored by the core as elastic deformation of the mantle and icy core. It is concluded that because the cometary materials are almost certainly brittle and the icy core is likely to be self lubricating, the elastic rebound and gas pressure expulsion forces must be counteracted by forces greater than those that may be provided by a piercing device or its capture devices (barbs).

  7. LIQUID PHASE SINTERED METAL MATRIX COMPOSITE MATERIALS

    Microsoft Academic Search

    S. J. Yankee; G. M. Janowski; B. J. Pletka

    1990-01-01

    Iron-base and aluminum-base composite materials reinforced with various ceramic particulates have been fabricated via powder metallurgy and liquid phase sintering. The advantage of this manufacturing route is that conventional powder metallurgy processing equipment can be used to fabricate metal matrix\\/ceramic composites. Furthermore, this approach makes it possible to manufacture these composites to near-net-shape. A number of matrix\\/ceramic combinations have been

  8. NASA Thermographic Inspection of Advanced Composite Materials

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott

    2004-01-01

    As the use of advanced composite materials continues to increase in the aerospace community, the need for a quantitative, rapid, in situ inspection technology has become a critical concern throughout the industry. In many applications it is necessary to monitor changes in these materials over an extended period of time to determine the effects of various load conditions. Additionally, the detection and characterization of defects such as delaminations, is of great concern. This paper will present the application of infrared thermography to characterize various composite materials and show the advantages of different heat source types. Finally, various analysis methodologies used for quantitative material property characterization will be discussed.

  9. Composite Materials for Wind Power Turbine Blades

    Microsoft Academic Search

    Povl Brøndsted; Hans Lilholt; Aage Lystrup

    2005-01-01

    Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites

  10. Powder Metallurgy Composite Materials Strengthened with Fibers

    Microsoft Academic Search

    Suren G. Agbalyan

    2001-01-01

    The extrusion dynamics of high-strength powder metallurgy composite materials was studied. The extrusion parameters for porous compacts of copper fibers and Cu ? Mo composites were optimized. It was shown that orientation of fibers is possible only when they are sufficiently widely dispersed in the powder matrix and also when the fiber length is much greater than its diameter l

  11. Automotive applications for advanced composite materials

    Microsoft Academic Search

    Deutsch

    1978-01-01

    A description is presented of nonaerospace applications for advanced composite materials with special emphasis on the automotive applications. The automotive industry has to satisfy exacting requirements to reduce the average fuel consumption of cars. A feasible approach to accomplish this involves the development of composites cars with a total weight of 2400 pounds and a fuel consumption of 33 miles

  12. Self-healing structural composite materials

    Microsoft Academic Search

    M. R. Kessler; N. R. Sottos; S. R. White

    2003-01-01

    A self-healing fiber-reinforced structural polymer matrix composite material is demonstrated. In the composite, a microencapsulated healing agent and a solid chemical catalyst are dispersed within the polymer matrix phase. Healing is triggered by crack propagation through the microcapsules, which then release the healing agent into the crack plane. Subsequent exposure of the healing agent to the chemical catalyst initiates polymerization

  13. Method to fabricate layered material compositions

    DOEpatents

    Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM)

    2002-01-01

    A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

  14. Acoustic emission monitoring of polymer composite materials

    NASA Technical Reports Server (NTRS)

    Bardenheier, R.

    1981-01-01

    The techniques of acoustic emission monitoring of polymer composite materials is described. It is highly sensitive, quasi-nondestructive testing method that indicates the origin and behavior of flaws in such materials when submitted to different load exposures. With the use of sophisticated signal analysis methods it is possible the distinguish between different types of failure mechanisms, such as fiber fracture delamination or fiber pull-out. Imperfections can be detected while monitoring complex composite structures by acoustic emission measurements.

  15. Composite materials with improved phyllosilicate dispersion

    DOEpatents

    Chaiko, David J.

    2004-09-14

    The present invention provides phyllosilicates edge modified with anionic surfactants, composite materials made from the edge modified phyllosilicates, and methods for making the same. In various embodiments the phyllosilicates are also surface-modified with hydrophilic lipophilic balance (HLB) modifying agents, polymeric hydrotropes, and antioxidants. The invention also provides blends of edge modified phyllosilicates and semicrystalline waxes. The composite materials are made by dispersing the edge modified phyllosilicates with polymers, particularly polyolefins and elastomers.

  16. Composite materials: composition, properties and clinical applications. A literature review.

    PubMed

    Zimmerli, Brigitte; Strub, Matthias; Jeger, Franziska; Stadler, Oliver; Lussi, Adrian

    2010-01-01

    Various composite materials are available today for direct restorative techniques. The most well-known materials are the hybrid composites. This technology, based on methacrylates and different types of filler coupled with silanes, has been continuously improved. Disadvantages such as polymerisation shrinkage, bacterial adhesion and side effects due to monomer release still remain. The aim of material development is to eliminate or at least reduce these negative factors by adapting the individual components of the material. With ormocers, the methacrylate has been partially replaced by an inorganic network. According to recent studies, the biocompatibility was not improved in all cases. The development of compomer was an attempt to combine the positive properties of glassionomers with composite technology. This has only partially succeeded, because the fluoride release is low. In an in-situ study, a caries protective effect could be shown at least in the first days following filling placement with concurrent extra-oral demineralisation. By replacing the chain-monomers in the composite matrix by ring-shaped molecules, a new approach to reduce polymerisation shrinkage was investigated. A new group of materials, the siloranes, has been developed. Siloranes are hydrophobic and need to be bonded to the dental hard tissue using a special adhesive system. Long-term clinical studies are still needed to prove the superiority of this new group of materials over modern hybrid composites. PMID:21243545

  17. Ceramic composites: Enabling aerospace materials

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  18. Graphene-based Composite Materials

    NASA Astrophysics Data System (ADS)

    Rafiee, Mohammad Ali

    We investigated the mechanical properties, such as fracture toughness (KIc), fracture energy (GIc), ultimate tensile strength (UTS), Young¡¦s modulus (E), and fatigue crack propagation rate (FCPR) of epoxy-matrix composites with different weight fractions of carbon-based fillers, including graphene platelets (GPL), graphene nanoribbons (GNR), single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), and fullerenes (C60). Only ˜0.125 wt.% GPL was found to increase the KIc of the pure epoxy by ˜65% and the GIc by ˜115%. To get similar improvement, CNT and nanoparticle epoxy composites required one to two orders of magnitude greater weight fraction of nanofillers. Moreover, ˜0.125% wt.% GPL also decreased the fatigue crack propagation rate in the epoxy by ˜30-fold. The E value of 0.1 wt.% GPL/epoxy nanocomposite was ˜31% larger than the pure epoxy while there was only an increase of ˜3% for the SWNT composites. The UTS of the pristine epoxy was improved by ˜40% with GPLs in comparison with ˜14% enhancement for the MWNTs. The KIc of the GPL nanocomposite enhanced by ˜53% over the pristine epoxy compared to a ˜20% increase for the MWNT-reinforced composites. The results of the FCPR tests for the GPL nanocomposites showed a different trend. While the CNT nanocomposites were not effective enough to suppress the crack growth at high values of the stress intensity factor (DeltaK), the reverse behavior is observed for the GPL nanocomposites. The advantage of the GPLs over CNTs in terms of mechanical properties enhancement is due to their enormous specific surface area, enhanced adhesion at filler/epoxy interface (because of the wrinkled surfaces of GPLs), as well as the planar structure of the GPLs. We also show that unzipping of MWNTs into graphene nanoribbons (GNRs) enhances the load transfer effectiveness in epoxy nanocomposites. For instance, at ˜0.3 wt.% of fillers, the Young's modulus (E) of the epoxy nanocomposite with GNRs increased by ˜30% compared to their MWNTs counterpart. The ultimate tensile strength (UTS) for ˜0.3 wt.% GNR composites showed ˜22% enhancement compared to the MWNT composites at the same loading fraction of fillers (at ˜0.3 wt.%). Our results show that unzipping effect can be used to transform carbon nanotubes into graphene nanoribbons, which are far more effective than the baseline nanotube as a nanofiller in nanocomposites. The mechanical properties of fullerence (C60) epoxy nanocomposites at different loading fractions (wt.%) of fullerene fillers in the pristine epoxy was also studied. Fullerene (C60) fillers demonstrated good potential to improve the mechanical properties of epoxy composites. However the required C60 loading fractions were ˜1% which are still an order of magnitude higher than that for graphene platelets (˜0.1%). This again illustrates the superiority of graphene as a structural reinforcement additive for epoxy polymers at low nanofiller loadings. While the main focus of this work has been on epoxy polymers, initial results with ceramic matrix and metal (aluminum) matrix composites were also generated. These results demonstrate that GPL are highly effective in enahncing the fracture properties of silicon nitride ceramics. The fracture toughness of the baseline silicon nitride matrix increased by ˜235% (from ˜2.8 to ˜6.6 MPa.m1/2) at ˜1.5% GPL volume fraction. However the results were disappointing for aluminim matrix composites. Compared to the pure aluminum, the graphene-aluminum composites showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler. These results indicate that Graphene Platelets (GPL) show strong potential as a nanofiller for epoxy nanocomposites and can provide a performance comparable to other forms of nanofillers at a significantly lower nanofiller loading fraction.

  19. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    SciTech Connect

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested under simulated usage and accident conditions. Mitigating the hazards associated with reactive metal hydrides during an accident while finding a way to keep the original capability of the active material intact during normal use has been the focus of this work. These composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride, in this case a prepared sodium alanate (chosen as a representative reactive metal hydride). It was found that the polymerization of styrene and divinyl benzene could be initiated using AIBN in toluene at 70 degC. The resulting composite materials can be either hard or brittle solids depending on the cross-linking density. Thermal decomposition of these styrene-based composite materials is lower than neat polystyrene indicating that the chemical nature of the polymer is affected by the formation of the composite. The char-forming nature of cross-linked polystyrene is low and therefore, not an ideal polymer for hazard mitigation. To obtain composite materials containing a polymer with higher char-forming potential, siloxane-based monomers were investigated. Four vinyl-containing siloxane oligomers were polymerized with and without added styrene and divinyl benzene. Like the styrene materials, these composite materials exhibited thermal decomposition behavior significantly different than the neat polymers. Specifically, the thermal decomposition temperature was shifted approximately 100 degC lower than the neat polymer signifying a major chemical change to the polymer network. Thermal analysis of the cycled samples was performed on the siloxane-based composite materials. It was found that after 30 cycles the siloxane-containing polymer composite material has similar TGA/DSC-MS traces as the virgin composite material indicating that the polymer is physically intact upon cycling. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride in the form of a composite material reduced the inherent hydrogen storage capacity of the material. This

  20. Oxygen Compatibility Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Graf, Neil A.; Hudgins, Richard J.; McBain, Michael

    2000-01-01

    The development of polymer composite liquid oxygen LO2 tanks is a critical step in creating the next generation of launch vehicles. Future launch vehicles need to minimize the gross liftoff weight (GLOW), which is possible due to the 25%-40% reduction in weight that composite materials could provide over current aluminum technology. Although a composite LO2 tank makes these weight savings feasible, composite materials have not historically been viewed as "LO2 compatible." To be considered LO2 compatible, materials must be selected that will resist any type of detrimental, combustible reaction when exposed to usage environments. This is traditionally evaluated using a standard set of tests. However, materials that do not pass the standard tests can be shown to be safe for a particular application. This paper documents the approach and results of a joint NASA/Lockheed Martin program to select and verify LO2 compatible composite materials for liquid oxygen fuel tanks. The test approach developed included tests such as mechanical impact, particle impact, puncture, electrostatic discharge, friction, and pyrotechnic shock. These tests showed that composite liquid oxygen tanks are indeed feasible for future launch vehicles.

  1. Nonmetallic materials and composites at low temperatures

    SciTech Connect

    Hartwig, G.; Evans, D.

    1982-01-01

    This book presents articles by leading scientists who explore the cryogenic behavior of such materials as epoxies, polyethylenes, polymers, various composites, and glasses. Examines the thermal and dielectric properties of these materials, as well as their elasticity, cohesive strength, resistance to strain and fracturing, and applications. Topics include thermal properties of crystalline polymers; thermal conductivity in semicrystalline polymers; ultrasonic absorption in polymethylmethacrylate; radiation damage in thin sheet fiberglass; epoxide resins; dynamic mechanical properties of poly (methacrylates); dielectric loss due to antioxidants in polyolefins; fracture measurements on polyethylene in comparison with epoxy resins; fatigue testing of epoxide resins; lap testing of epoxide resins; thermal conductivity and thermal expansion of non-metallic composite materials; nonlinear stresses and displacements of the fibers and matrix in a radially loaded circular composite ring; the strain energy release rate of glass fiber-reinforced polyester composites; charpy impact testing of cloth reinforced epoxide resin; nonmetallic and composite materials as solid superleaks; carbon fiber reinforced expoxide resins; standardizing nonmetallic composite materials.

  2. Interfacial interaction and adhesion in composite materials

    Microsoft Academic Search

    R. Y. Yee; E. C. Martin

    1984-01-01

    The interfacial interaction of composites plays an important role in the properties of material such as structural materials, solid propellants, and explosives. To study the interfacial interaction, surface and interfacial free energies were investigated. The wettability of solids was determined by the Wilhelmy plate method using a series of reference liquids. The surface free energies of these solids were calculated

  3. Structured Piezoelectric Composites: Materials and Applications

    Microsoft Academic Search

    D. A. Van den Ende

    2012-01-01

    The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits their practical application to certain specific fields. Piezoelectric composites, which contain an active piezoelectric (ceramic) phase in a

  4. NASA Thermographic Inspection of Advanced Composite Materials

    Microsoft Academic Search

    K. Elliott Cramer

    As the use of advanced composite materials continues to increase in the aerospace community, the need for a quantitative, rapid, in situ inspection technology has become a critical concern throughout the industry. In many applications it is necessary to monitor changes in these materials over an extended period of time to determine the effects of various load conditions. Additionally, the

  5. A physically-based abrasive wear model for composite materials

    SciTech Connect

    Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.

    2001-05-01

    A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

  6. ISOTOPIC COMPOSITIONS OF URANIUM REFERENCE MATERIALS

    SciTech Connect

    Jacobsen, B; Borg, L; Williams, R; Brennecka, G; Hutcheon, I

    2009-09-03

    Uranium isotopic compositions of a variety of U standard materials were measured at Lawrence Livermore National Laboratory and are reported here. Both thermal ionization mass spectrometry (TIMS) and multi-collector inductively couple plasma mass spectrometry (MC-ICPMS) were used to determine ratios of the naturally occurring isotopes of U. Establishing an internally coherent set of isotopic values for a range of U standards is essential for inter-laboratory comparison of small differences in {sup 238}U/{sup 235}U, as well as the minor isotopes of U. Differences of {approx} 1.3{per_thousand} are now being observed in {sup 238}U/{sup 235}U in natural samples, and may play an important role in understanding U geochemistry where tracing the origin of U is aided by U isotopic compositions. The {sup 238}U/{sup 235}U ratios were measured with a TRITON TIMS using a mixed {sup 233}U-{sup 236}U isotopic tracer to correct for instrument fractionation. this tracer was extremely pure and resulted in only very minor corrections on the measured {sup 238}U/{sup 235}U ratios of {approx} 0.03. The values obtained for {sup 238}U/{sup 235}U are: IRMM184 = 137.698 {+-} 0.020 (n = 15), SRM950a = 137.870 {+-} 0.018 (n = 8), and CRM112a = 137.866 {+-} 0.030 (n = 16). Uncertainties represent 2 s.d. of the population. The measured value for IRMM184 is in near-perfect agreement with the certified value of 137.697 {+-} 0.042. However, the U isotopic compositions of SRM950a and CRM112a are not certified. Minor isotopes of U were determined with a Nu Plasma HR MC-ICPMS and mass bias was corrected by sample/standard bracketing to IRMM184, using its certified {sup 238}U/{sup 235}U ratio. Thus, the isotopic compositions determined using both instruments are compatible. The values obtained for {sup 234}U/{sup 235}U are: SRM950a = (7.437 {+-} 0.043) x 10{sup -3} (n = 18), and CRM112a = (7.281 {+-} 0.050) x 10{sup -3} (n = 16), both of which are in good agreement with published values. The value for {sup 236}U/{sup 235}U in SRM950a was determined to be (8.48 {+-} 2.63) x 10{sup -6}, whereas {sup 236}U was not detected in CRM112a. They are currently obtaining the U isotopic composition of CRM129a. Preliminary results suggest that the {sup 238}U/{sup 235}U ratio is within error, but slightly lower than the certified value of 137.71.

  7. Impact testing of textile composite materials

    NASA Technical Reports Server (NTRS)

    Portanova, Marc

    1995-01-01

    The objectives of this report were to evaluate the impact damage resistance and damage tolerance of a variety of textile composite materials. Static indentation and impact tests were performed on the stitched and unstitched uniweave composites constructed from AS4/3501-6 Carbon/Epoxy with a fiberglass yarn woven in to hold the fibers together while being stitched. Compression and tension were measured after the tests to determine the damage resistance, residual strength and the damage tolerance of the specimens.

  8. Computational modeling of composite material fires.

    SciTech Connect

    Brown, Alexander L.; Erickson, Kenneth L.; Hubbard, Joshua Allen; Dodd, Amanda B.

    2010-10-01

    Composite materials behave differently from conventional fuel sources and have the potential to smolder and burn for extended time periods. As the amount of composite materials on modern aircraft continues to increase, understanding the response of composites in fire environments becomes increasingly important. An effort is ongoing to enhance the capability to simulate composite material response in fires including the decomposition of the composite and the interaction with a fire. To adequately model composite material in a fire, two physical model development tasks are necessary; first, the decomposition model for the composite material and second, the interaction with a fire. A porous media approach for the decomposition model including a time dependent formulation with the effects of heat, mass, species, and momentum transfer of the porous solid and gas phase is being implemented in an engineering code, ARIA. ARIA is a Sandia National Laboratories multiphysics code including a range of capabilities such as incompressible Navier-Stokes equations, energy transport equations, species transport equations, non-Newtonian fluid rheology, linear elastic solid mechanics, and electro-statics. To simulate the fire, FUEGO, also a Sandia National Laboratories code, is coupled to ARIA. FUEGO represents the turbulent, buoyantly driven incompressible flow, heat transfer, mass transfer, and combustion. FUEGO and ARIA are uniquely able to solve this problem because they were designed using a common architecture (SIERRA) that enhances multiphysics coupling and both codes are capable of massively parallel calculations, enhancing performance. The decomposition reaction model is developed from small scale experimental data including thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) in both nitrogen and air for a range of heating rates and from available data in the literature. The response of the composite material subject to a radiant heat flux boundary condition is examined to study the propagation of decomposition fronts of the epoxy and carbon fiber and their dependence on the ambient conditions such as oxygen concentration, surface flow velocity, and radiant heat flux. In addition to the computational effort, small scaled experimental efforts to attain adequate data used to validate model predictions is ongoing. The goal of this paper is to demonstrate the progress of the capability for a typical composite material and emphasize the path forward.

  9. School of Mechanical and Materials Engineering Composites Materials and Engineering Center

    E-print Network

    Collins, Gary S.

    program, classroom teaching in the area of mechanical or materials engineering, and serviceSchool of Mechanical and Materials Engineering and Composites Materials and Engineering Center and Materials Engineering (MME) in collaboration with the Composites Materials and Engineering Center (CMEC

  10. Thermal expansion properties of composite materials

    NASA Technical Reports Server (NTRS)

    Johnson, R. R.; Kural, M. H.; Mackey, G. B.

    1981-01-01

    Thermal expansion data for several composite materials, including generic epoxy resins, various graphite, boron, and glass fibers, and unidirectional and woven fabric composites in an epoxy matrix, were compiled. A discussion of the design, material, environmental, and fabrication properties affecting thermal expansion behavior is presented. Test methods and their accuracy are discussed. Analytical approaches to predict laminate coefficients of thermal expansion (CTE) based on lamination theory and micromechanics are also included. A discussion is included of methods of tuning a laminate to obtain a near-zero CTE for space applications.

  11. Natural melanin composites by layer-by-layer assembly

    NASA Astrophysics Data System (ADS)

    Eom, Taesik; Shim, Bong Sub

    2015-04-01

    Melanin is an electrically conductive and biocompatible material, because their conjugated backbone structures provide conducting pathways from human skin, eyes, brain, and beyond. So there is a potential of using as materials for the neural interfaces and the implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in mostly polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL counterpart to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, electrical properties, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), multimeter, and in-vitro cell test of PC12, respectively.

  12. Frictional Ignition Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Peralta, Steve; Rosales, Keisa; Robinson, Michael J.; Stoltzfus, Joel

    2006-01-01

    The space flight community has been investigating lightweight composite materials for use in propellant tanks for both liquid and gaseous oxygen for space flight vehicles. The use of these materials presents some risks pertaining to ignition and burning hazards in the presence of oxygen. Through hazard analysis process, some ignition mechanisms have been identified as being potentially credible. One of the ignition mechanisms was reciprocal friction; however, test data do not exist that could be used to clear or fail these types of materials as "oxygen compatible" for the reciprocal friction ignition mechanism. Therefore, testing was performed at White Sands Test Facility (WSTF) to provide data to evaluate this ignition mechanism. This paper presents the test system, approach, data results, and findings of the reciprocal friction testing performed on composite sample materials being considered for propellant tanks.

  13. Testing of NCSX Composite Coil Material Properties

    SciTech Connect

    Kozub, Thomas; Jurczynski, Stephan; Chrzanowski, James [Princeton Plasma Physics Laboratory (United States)

    2005-05-15

    The National Compact Stellarator Experiment (NCSX) is now in design and requires 18 modular coils that are constructed to a highly complex geometry. The modular coil conductors are designed as a composite of a fine gauge stranded copper cable shaped to the required geometry and vacuum impregnated with a resin. These composite conductors exhibit unique material properties that must be determined and verified through testing. The conductor material properties are necessary for design modeling and performance validation. This paper will present the methods used to test and measure the coil conductor material properties, the unique challenges in measuring these complex materials at both room and liquid nitrogen temperatures and the results of those tests.

  14. Ground exposure of composite materials for helicopters

    NASA Technical Reports Server (NTRS)

    Baker, D. J.

    1984-01-01

    Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.

  15. Early Fatigue Damage Detection in Composite Materials

    Microsoft Academic Search

    J. J. Nevadunsky; J. J. Lucas; M. J. Salkind

    1975-01-01

    Detection of early fatigue damage in composite materials by nondestructive inspection (NDI) techniques has been demonstrated for ±45° Glass\\/Epoxy, and ±45°\\/0° Graphite\\/Glass\\/Epoxy. Dynamic axial modulus and temperature were monitored continuously with a correlation between temperature rise and modulus decrease observed. The modulus decrease and temperature rise are indicative of irreversible damage in these materials.Torsional modulus measurements and coin tap tests

  16. Composite materials for rail transit systems

    NASA Technical Reports Server (NTRS)

    Griffin, O. Hayden, Jr.; Guerdal, Zafer; Herakovich, Carl T.

    1987-01-01

    The potential is explored for using composite materials in urban mass transit systems. The emphasis was to identify specific advantages of composite materials in order to determine their actual and potential usage for carbody and guideway structure applications. The literature was reviewed, contacts were made with major domestic system operators, designers, and builders, and an analysis was made of potential composite application to railcar construction. Composites were found to be in use throughout the transit industry, usually in secondary or auxiliary applications such as car interior and nonstructural exterior panels. More recently, considerable activity has been initiated in the area of using composites in the load bearing elements of civil engineering structures such as highway bridges. It is believed that new and improved manufacturing refinements in pultrusion and filament winding will permit the production of beam sections which can be used in guideway structures. The inherent corrosion resistance and low maintenance characteristics of composites should result in lowered maintenance costs over a prolonged life of the structure.

  17. Fungal degradation of fiber-reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Gu, J. D.; Lu, C.; Mitchell, R.; Thorp, K.; Crasto, A.

    1997-01-01

    As described in a previous report, a fungal consortium isolated from degraded polymeric materials was capable of growth on presterilized coupons of five composites, resulting in deep penetration into the interior of all materials within five weeks. Data describing the utilization of composite constituents as nutrients for the microflora are described in this article. Increased microbial growth was observed when composite extract was incubated with the fungal inoculum at ambient temperatures. Scanning electron microscopic observation of carbon fibers incubated with a naturally developed population of microorganisms showed the formation of bacterial biofilms on the fiber surfaces, suggesting possible utilization of the fiber chemical sizing as carbon and energy sources. Electrochemical impedance spectroscopy was used to monitor the phenomena occurring at the fiber-matrix interfaces. Significant differences were observed between inoculated and sterile panels of the composite materials. A progressive decline in impedance was detected in the inoculated panels. Several reaction steps may be involved in the degradation process. Initial ingress of water into the resin matrix appeared to be followed by degradation of fiber surfaces, and separation of fibers from the resin matrix. This investigation suggested that composite materials are susceptible to microbial attack by providing nutrients for growth.

  18. Characterization of self-healing composite materials

    Microsoft Academic Search

    Kevin John Ford

    2006-01-01

    Damage occurs in almost every composite material in the form of microcracks that develop in the epoxy matrix that binds the fibers together. Researchers at the University of Illinois Urbana Champaign have recently developed a method to reverse the effects of, or heal, damage in the epoxy matrix. Their in-situ self-healing system uses embedded microcapsules and a catalyst that trigger

  19. Computer aided design of multifunctional composite materials

    Microsoft Academic Search

    V. V. Kafarov; I. N. Dorokhov; A. Ramirez; N. I. Kafarova

    1996-01-01

    This paper deal with a multicriterion compromise problem of production of a multifunctional material on the basis of a stochastic composite with several mutually distributed phases. A formal technique for solving this problem is proposed based on the methods of topological feedback, mathematical morphology, percolation theory, and the theory of discrete phase mappings. By way of illustration, this formal technique

  20. Plastic working of laminated composite materials

    Microsoft Academic Search

    S. V. Voronov; D. G. Devoino

    1982-01-01

    Plastic working can be successfully employed for increasing the strength of the joint in a laminated composite material whose components react with each other during high-speed cladding, with the formation of brittle intermetallic compouds. At the same time, by suitable choice of reduction and mismatch, it is possible to produce straight bimetallic strips by rolling them with mismatched peripheral roll

  1. Mechanical properties of some composite materials

    Microsoft Academic Search

    S. A. Golovin; V. S. Zuev

    1976-01-01

    It is commonly believed that steels and alloys based on heat-resistant metals have low damping properties and limited endurance. However, the development of new composite materials (based on these metals) with heterogeneous structure, consisting of a rigid matrix and soft inclusions, has made it possible to obtain alloys with special properties. Sintering and impregnation are particularly important during production of

  2. Moisture Absorption and Desorption of Composite Materials

    Microsoft Academic Search

    Chi-Hung Shen; George S. Springer

    1976-01-01

    Expressions are presented for the moisture distribution and the mois ture content as a function of time of one dimensional homogeneous and composite materials exposed either on one side or on both sides to humid air or to water. The results apply during both moisture absorption and desorption when the moisture content and the temperature of the environ ment are

  3. Composite materials in flexible multibody systems

    Microsoft Academic Search

    Maria Augusta Neto; Jorge A. C. Ambrósio; Rogério P. Leal

    2006-01-01

    In this work the flexible multibody dynamics formulations of complex models are extended to include elastic components made of laminated composite materials. The only limitation for the deformation of a structural member is that it must be elastic and linear when described in a body fixed frame. A finite element model for each flexible body is obtained such that the

  4. INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS 1 Introduction

    E-print Network

    Boyer, Edmond

    are injected by a low viscosity resin. During this process, we have to pay particular attention to the void materials can be elaborated by Liquid Composite Molding (LCM), a family of processes where fibrous preforms flow rates. Liquid is injected in the T- shaped junction by two syringe compressors in setting two

  5. Mishap risk control for advanced aerospace/composite materials

    NASA Technical Reports Server (NTRS)

    Olson, John M.

    1994-01-01

    Although advanced aerospace materials and advanced composites provide outstanding performance, they also present several unique post-mishap environmental, safety, and health concerns. The purpose of this paper is to provide information on some of the unique hazards and concerns associated with these materials when damaged by fire, explosion, or high-energy impact. Additionally, recommended procedures and precautions are addressed as they pertain to all phases of a composite aircraft mishap response, including fire-fighting, investigation, recovery, clean-up, and guidelines are general in nature and not application-specific. The goal of this project is to provide factual and realistic information which can be used to develop consistent and effective procedures and policies to minimize the potential environmental, safety, and health impacts of a composite aircraft mishap response effort.

  6. Development of a novel regenerated cellulose composite material.

    PubMed

    De Silva, Rasike; Vongsanga, Kylie; Wang, Xungai; Byrne, Nolene

    2015-05-01

    We report for the first time on a new natural composite material achieved by blending cotton and duck feather using an ionic liquid. The addition of duck feather was found to improve the elasticity, strain at break, by 50% when compared to regenerated cellulose alone. This is a significant finding since regenerated cotton using ionic liquids often suffers from poor elasticity. The improved elasticity is likely due to the regenerated duck feather maintaining its helical structure. The new regenerated cellulose composites were characterized using a combination of dynamic mechanical analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis, contact angle measurements and scanning electron microscopy. PMID:25659713

  7. NATURE MATERIALS | VOL 13 | MARCH 2014 | www.nature.com/naturematerials 233 hotovoltaic devices --which convert abundant, free solar

    E-print Network

    seek to fulfil this goal. Efficient harvesting of the wide dispersion of photon energies that make up by engineering the composition and structure of the electrode materials that contact the colloidal quantum dotNATURE MATERIALS | VOL 13 | MARCH 2014 | www.nature.com/naturematerials 233 P hotovoltaic devices

  8. Autophagous spacecraft composite materials for orbital propulsion

    NASA Astrophysics Data System (ADS)

    Joshi, Prakash; Upschulte, Bernard L.; Gelb, Alan H.; Green, B. David; Lester, Dean M.; Wallace, Ingvar; Starrett, W. David; Marshall, David W.

    2002-07-01

    We are developing structural polymer composite materials that can be converted into fuels and combusted with oxidizers for orbital propulsion of spacecraft. We have identified candidate materials and demonstrated sustained combustion with nitrogen tetroxide (NTO) as an oxidizer. To improve reaction chemistry we have evaluated several energetic additives. Detailed material compatibility tests were conducted to identify stable combinations of structural polymer and energetic additives. We have also demonstrated sustained combustion of structural polymeric materials with embedded additives and NTO. In the next phase of research, we plan to investigate hydrogen peroxide as the oxidizer. Samples of composites comprising thin metallic facesheets, structural polymer propellant matrix, and metallic mesh reinforcements (that also serve as electrical heaters/igniters for pyrolysis) were fabricated and their mechanical properties were measured. Concept of a spacecraft structural stringer, which also functions as a thruster, was developed using the composite material formulation. Both all solid and hybrid stringer-thruster designs have been developed. Prototype stringer-thrusters will be fabricated and tested in Phase II.

  9. ACEE Composite Structures Technology: Review of selected NASA research on composite materials and structures

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The NASA Aircraft Energy Efficiency (ACEE) Composite Primary Aircraft Structures Program was designed to develop technology for advanced composites in commercial aircraft. Research on composite materials, aircraft structures, and aircraft design is presented herein. The following parameters of composite materials were addressed: residual strength, damage tolerance, toughness, tensile strength, impact resistance, buckling, and noise transmission within composite materials structures.

  10. Study of dielectric relaxation spectra of composite materials by the dielectric spectroscopy method

    Microsoft Academic Search

    O. S. Gefle; S. M. Lebedev; Y. P. Pokholkov; S. N. Tkachenko; V. A. Volokhin; E. I. Cherkashina

    2005-01-01

    In this paper composite solid dielectrics were studied by using the dielectric spectroscopy method in frequency domain. Dielectric relaxation spectra of composite materials on the basis of natural and synthetic rubbers and LDPE filled with a ferroelectric ceramic powder PZT (lead zirconate titanate) were studied. The filled composites with high permittivity were used in HV insulation for the electric field

  11. Aluminum composite materials for multichip modules

    NASA Astrophysics Data System (ADS)

    Premkumar, M. K.; Hunt, W. H.; Sawtell, R. R.

    1992-07-01

    In the intensive materials development activities for electronic packaging and thermal management applications, the subclass of materials in which SiC particles reinforce aluminum alloy matrices has emerged as one with an especially attractive combination of physical properties, manufacturing flexibility, and cost. One benefit of these materials is the ability to tailor the physical properties through the selection of both reinforcement and alloy variables to match the thermal expansion coefficient of other electronic materials. In addition, the manufacturing flexibility of the various processes allows for shape complexity as well as selective reinforcement placement in the component to optimize system producibility. Finally, because raw materials are inherently inexpensive and low-cost production routes have been identified, aluminum composites may offer a range of cost-effective solutions to emerging problems in electronic packaging and thermal-management applications.

  12. Conductor-polymer composite electrode materials

    DOEpatents

    Ginley, D.S.; Kurtz, S.R.; Smyrl, W.H.; Zeigler, J.M.

    1984-06-13

    A conductive composite material useful as an electrode, comprises a conductor and an organic polymer which is reversibly electrochemically dopable to change its electrical conductivity. Said polymer continuously surrounds the conductor in intimate electrical contact therewith and is prepared by electrochemical growth on said conductor or by reaction of its corresponding monomer(s) on said conductor which has been pre-impregnated or pre-coated with an activator for said polymerization. Amount of the conductor is sufficient to render the resultant composite electrically conductive even when the polymer is in an undoped insulating state.

  13. Dielectric breakdown model for composite materials.

    PubMed

    Peruani, F; Solovey, G; Irurzun, I M; Mola, E E; Marzocca, A; Vicente, J L

    2003-06-01

    This paper addresses the problem of dielectric breakdown in composite materials. The dielectric breakdown model was generalized to describe dielectric breakdown patterns in conductor-loaded composites. Conducting particles are distributed at random in the insulating matrix, and the dielectric breakdown propagates according to new rules to take into account electrical properties and particle size. Dielectric breakdown patterns are characterized by their fractal dimension D and the parameters of the Weibull distribution. Studies are carried out as a function of the fraction of conducting inhomogeneities, p. The fractal dimension D of electrical trees approaches the fractal dimension of a percolation cluster when the fraction of conducting particles approximates the percolation limit. PMID:16241318

  14. Compression Testing of Textile Composite Materials

    NASA Technical Reports Server (NTRS)

    Masters, John E.

    1996-01-01

    The applicability of existing test methods, which were developed primarily for laminates made of unidirectional prepreg tape, to textile composites is an area of concern. The issue is whether the values measured for the 2-D and 3-D braided, woven, stitched, and knit materials are accurate representations of the true material response. This report provides a review of efforts to establish a compression test method for textile reinforced composite materials. Experimental data have been gathered from several sources and evaluated to assess the effectiveness of a variety of test methods. The effectiveness of the individual test methods to measure the material's modulus and strength is determined. Data are presented for 2-D triaxial braided, 3-D woven, and stitched graphite/epoxy material. However, the determination of a recommended test method and specimen dimensions is based, primarily, on experimental results obtained by the Boeing Defense and Space Group for 2-D triaxially braided materials. They evaluated seven test methods: NASA Short Block, Modified IITRI, Boeing Open Hole Compression, Zabora Compression, Boeing Compression after Impact, NASA ST-4, and a Sandwich Column Test.

  15. Multifunctional composite materials for catalysis and chemical mechanical planarization

    Microsoft Academic Search

    Cecil A. Coutinho

    2009-01-01

    Composite materials formed from two or more functionally different materials offer a versatile avenue to create a tailored material with well defined traits. Within this dissertation research, multi-functional composites were synthesized based on organic and inorganic materials. The functionally of these composites was experimentally tested and a semi-empirical model describing the sedimentation behavior of these particles was developed. This first

  16. Research Progress on Intercalation Composite Materials based on Kaolin

    Microsoft Academic Search

    Pan Xiaobing; Li Yanfeng; Liu Gang; Men Xuehu

    2004-01-01

    Kaolin is a nonmetal resource with abundant storage, and it would be changed into one of organic\\/inorganic composite materials by means of intercalating modification. Comparing with general composite materials, intercalation composite material is formed by intercalating one or more layers either organic molecules or polymers into inorganic materials with stratum shape, its mechanical properties could be modified markedly. The characteristics

  17. Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites

    Microsoft Academic Search

    Bettye L. Smith; Tilman E. Schäffer; Mario Viani; James B. Thompson; Neil A. Frederick; Johannes Kindt; Angela Belcher; Galen D. Stucky; Daniel E. Morse; Paul K. Hansma

    1999-01-01

    Natural materials are renowned for their strength and toughness,,,,. Spider dragline silk has a breakage energy per unit weight two orders of magnitude greater than high tensile steel,, and is representative of many other strong natural fibres,,. The abalone shell, a composite of calcium carbonate plates sandwiched between organic material, is 3,000 times more fracture resistant than a single crystal

  18. Stressed environmental degradation of automotive composite materials

    SciTech Connect

    Henshaw, J.M.; Meyer, L.J. [Univ. of Tulsa, OK (United States); Houston, D.Q.; Hagerman, E.M.

    1997-12-31

    The degradation of mechanical properties due to exposure to various automotive environments during constant stress or constant strain loading is investigated. Two composites are studied. Each is a polyurethane reinforced with continuous strand E-glass mat, manufactured by the SRIM process. Novel fixtures apply tensile loads to dogbone-specimens while exposed to automotive fluids. After 300 hours, the specimens are tensile tested to failure in air. The effects of five fluids: distilled water, windshield washer fluid, brake fluid, gasoline, and sulfuric acid are examined on the first material. Extensive testing of both materials in distilled water gives a good comparison of the two materials and the effects of loading. Degradation in mechanical properties typically increases with stress level but is independent of the type of loading. This result is discussed in terms of damage and deformation mechanisms in the material.

  19. Novel Cryogenic Insulation Materials: Aerogel Composites

    NASA Technical Reports Server (NTRS)

    White, Susan

    2001-01-01

    New insulation materials are being developed to economically and reliably insulate future reusable spacecraft cryogenic tanks over a planned lifecycle of extreme thermal challenges. These insulation materials must prevent heat loss as well as moisture and oxygen condensation on the cryogenic tanks during extended groundhold, must withstand spacecraft launch conditions, and must protect a partly full or empty reusable cryogenic tank from significant reentry heating. To perform over such an extreme temperature range, novel composites were developed from aerogels and high-temperature matrix material such as Space Shuttle tile. These materials were fabricated and tested for use both as cryogenic insulation and as high-temperature insulation. The test results given in this paper were generated during spacecraft re-entry heating simulation tests using cryogenic cooling.

  20. Using Composite Materials in a Cryogenic Pump

    NASA Technical Reports Server (NTRS)

    Batton, William D.; Dillard, James E.; Rottmund, Matthew E.; Tupper, Michael L.; Mallick, Kaushik; Francis, William H.

    2008-01-01

    Several modifications have been made to the design and operation of an extended-shaft cryogenic pump to increase the efficiency of pumping. In general, the efficiency of pumping a cryogenic fluid is limited by thermal losses which is itself caused by pump inefficiency and leakage of heat through the pump structure. A typical cryogenic pump includes a drive shaft and two main concentric static components (an outer pressure containment tube and an intermediate static support tube) made from stainless steel. The modifications made include replacement of the stainless-steel drive shaft and the concentric static stainless-steel components with components made of a glass/epoxy composite. The leakage of heat is thus reduced because the thermal conductivity of the composite is an order of magnitude below that of stainless steel. Taking advantage of the margin afforded by the decrease in thermal conductivity, the drive shaft could be shortened to increase its effective stiffness, thereby increasing the rotordynamic critical speeds, thereby further making it possible to operate the pump at a higher speed to increase pumping efficiency. During the modification effort, an analysis revealed that substitution of the shorter glass/epoxy shaft for the longer stainless-steel shaft was not, by itself, sufficient to satisfy the rotordynamic requirements at the desired increased speed. Hence, it became necessary to increase the stiffness of the composite shaft. This stiffening was accomplished by means of a carbon-fiber-composite overwrap along most of the length of the shaft. Concomitantly with the modifications described thus far, it was necessary to provide for joining the composite-material components with metallic components required by different aspects of the pump design. An adhesive material formulated specially to bond the composite and metal components was chosen as a means to satisfy these requirements.

  1. Advanced Technology Composite Fuselage - Materials and Processes

    NASA Technical Reports Server (NTRS)

    Scholz, D. B.; Dost, E. F.; Flynn, B. W.; Ilcewicz, L. B.; Nelson, K. M.; Sawicki, A. J.; Walker, T. H.; Lakes, R. S.

    1997-01-01

    The goal of Boeing's Advanced Technology Composite Aircraft Structures (ATCAS) program was to develop the technology required for cost and weight efficient use of composite materials in transport fuselage structure. This contractor report describes results of material and process selection, development, and characterization activities. Carbon fiber reinforced epoxy was chosen for fuselage skins and stiffening elements and for passenger and cargo floor structures. The automated fiber placement (AFP) process was selected for fabrication of monolithic and sandwich skin panels. Circumferential frames and window frames were braided and resin transfer molded (RTM'd). Pultrusion was selected for fabrication of floor beams and constant section stiffening elements. Drape forming was chosen for stringers and other stiffening elements. Significant development efforts were expended on the AFP, braiding, and RTM processes. Sandwich core materials and core edge close-out design concepts were evaluated. Autoclave cure processes were developed for stiffened skin and sandwich structures. The stiffness, strength, notch sensitivity, and bearing/bypass properties of fiber-placed skin materials and braided/RTM'd circumferential frame materials were characterized. The strength and durability of cocured and cobonded joints were evaluated. Impact damage resistance of stiffened skin and sandwich structures typical of fuselage panels was investigated. Fluid penetration and migration mechanisms for sandwich panels were studied.

  2. Alkali metal protective garment and composite material

    SciTech Connect

    Ballif, J.L.; Yuan, W.W.

    1980-09-16

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium are described. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  3. Mechanics Methodology for Textile Preform Composite Materials

    NASA Technical Reports Server (NTRS)

    Poe, Clarence C., Jr.

    1996-01-01

    NASA and its contractors have completed a program to develop a basic mechanics underpinning for textile composites. Three major deliverables were produced by the program: 1. A set of test methods for measuring material properties and design allowables; 2. Mechanics models to predict the effects of the fiber preform architecture and constituent properties on engineering moduli, strength, damage resistance, and fatigue life; and 3. An electronic data base of coupon type test data. This report describes these three deliverables.

  4. Fiber Reinforced Composite Materials Used for Tankage

    NASA Technical Reports Server (NTRS)

    Cunningham, Christy

    2005-01-01

    The Nonmetallic Materials and Processes Group is presently working on several projects to optimize cost while providing effect materials for the space program. One factor that must be considered is that these materials must meet certain weight requirements. Composites contribute greatly to this effort. Through the use of composites the cost of launching payloads into orbit will be reduced to one-tenth of the current cost. This research project involved composites used for aluminum pressure vessels. These tanks are used to store cryogenic liquids during flight. The tanks need some type of reinforcement. Steel was considered, but added too much weight. As a result, fiber was chosen. Presently, only carbon fibers with epoxy resin are wrapped around the vessels as a primary source of reinforcement. Carbon fibers are lightweight, yet high strength. The carbon fibers are wet wound onto the pressure vessels. This was done using the ENTEC Filament Winding Machine. It was thought that an additional layer of fiber would aid in reinforcement as well as containment and impact reduction. Kevlar was selected because it is light weight, but five times stronger that steel. This is the same fiber that is used to make bullet-proof vests trampolines, and tennis rackets.

  5. Impact of solids on composite materials

    NASA Technical Reports Server (NTRS)

    Bronson, Arturo; Maldonado, Jerry; Chern, Tzong; Martinez, Francisco; Mccord-Medrano, Johnnie; Roschke, Paul N.

    1987-01-01

    The failure modes of composite materials as a result of low velocity impact were investigated by simulating the impact with a finite element analysis. An important facet of the project is the modeling of the impact of a solid onto cylindrical shells composed of composite materials. The model under development will simulate the delamination sustained when a composite material encounters impact from another rigid body. The computer equipment was installed, the computer network tested, and a finite element method model was developed to compare results with known experimental data. The model simulated the impact of a steel rod onto a rotating shaft. Pre-processing programs (GMESH and TANVEL) were developed to generate node and element data for the input into the three dimensional, dynamic finite element analysis code (DYNA3D). The finite element mesh was configured with a fine mesh near the impact zone and a coarser mesh for the impacting rod and the regions surrounding the impacting zone. For the computer simulation, five impacting loads were used to determine the time history of the stresses, the scribed surface areas, and the amount of ridging. The processing time of the computer codes amounted from 1 to 4 days. The calculated surface area were within 6-12 percent, relative error when compated to the actual scratch area.

  6. Industry to Education Technical Transfer Program & Composite Materials. Composite Materials Course. Fabrication I Course. Fabrication II Course. Composite Materials Testing Course. Final Report.

    ERIC Educational Resources Information Center

    Massuda, Rachel

    These four reports provide details of projects to design and implement courses to be offered as requirements for the associate degree program in composites and reinforced plastics technology. The reports describe project activities that led to development of curricula for four courses: composite materials, composite materials fabrication I,…

  7. Use of advanced composite materials for innovative building design solutions/

    E-print Network

    Lau, Tak-bun, Denvid

    2009-01-01

    Advanced composite materials become popular in construction industry for the innovative building design solutions including strengthening and retrofitting of existing structures. The interface between different materials ...

  8. Calcium phosphate-based composites as injectable bone substitute materials.

    PubMed

    Low, Kah Ling; Tan, Soon Huat; Zein, Sharif Hussein Sharif; Roether, Judith A; Mouriño, Viviana; Boccaccini, Aldo R

    2010-07-01

    A major weakness of current orthopedic implant materials, for instance sintered hydroxyapatite (HA), is that they exist as a hardened form, requiring the surgeon to fit the surgical site around an implant to the desired shape. This can cause an increase in bone loss, trauma to the surrounding tissue, and longer surgical time. A convenient alternative to harden bone filling materials are injectable bone substitutes (IBS). In this article, recent progress in the development and application of calcium phosphate (CP)-based composites use as IBS is reviewed. CP materials have been used widely for bone replacement because of their similarity to the mineral component of bone. The main limitation of bulk CP materials is their brittle nature and poor mechanical properties. There is significant effort to reinforce or improve the mechanical properties and injectability of calcium phosphate cement (CPC) and this review resumes different alternatives presented in this specialized literature. PMID:20336722

  9. Combustion synthesis of advanced composite materials

    SciTech Connect

    Moore, J.J. (Colorado School of Mines, Golden (United States))

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined. 10 refs.

  10. Glasses, ceramics, and composites from lunar materials

    NASA Astrophysics Data System (ADS)

    Beall, George H.

    1992-02-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  11. Combustion synthesis of advanced composite materials

    NASA Technical Reports Server (NTRS)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  12. Tablet-level origin of toughening in abalone shells and translation to synthetic composite materials

    Microsoft Academic Search

    Horacio D. Espinosa; Allison L. Juster; Felix J. Latourte; Owen Y. Loh; David Gregoire; Pablo D. Zavattieri

    2011-01-01

    Nacre, the iridescent material in seashells, is one of many natural materials employing hierarchical structures to achieve high strength and toughness from relatively weak constituents. Incorporating these structures into composites is appealing as conventional engineering materials often sacrifice strength to improve toughness. Researchers hypothesize that nacre's toughness originates within its brick-and-mortar-like microstructure. Under loading, bricks slide relative to each other,

  13. PERSPECTIVE: Self-healing polymer composites: mimicking nature to enhance performance

    Microsoft Academic Search

    R. S. Trask; H. R. Williams; I. P. Bond

    2007-01-01

    Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies

  14. Single-walled carbon nanotube networks in conductive composite materials.

    PubMed

    Bârsan, Oana A; Hoffmann, Günter G; van der Ven, Leo G J; de With, G Bert

    2014-01-01

    Electrically conductive composite materials can be used for a wide range of applications because they combine the advantages of a specific polymeric material (e.g., thermal and mechanical properties) with the electrical properties of conductive filler particles. However, the overall electrical behaviour of these composite materials is usually much below the potential of the conductive fillers, mainly because by mixing two different components, new interfaces and interphases are created, changing the properties and behaviours of both. Our goal is to characterize and understand the nature and influence of these interfaces on the electrical properties of composite materials. We have improved a technique based on the use of sodium carboxymethyl cellulose (CMC) to disperse single-walled carbon nanotubes (SWCNTs) in water, followed by coating glass substrates, and drying and removing the CMC with a nitric acid treatment. We used electron microscopy and atomic force microscopy techniques to characterize the SWCNT films, and developed an in situ resistance measurement technique to analyse the influence of both the individual components and the mixture of an epoxy/amine system on the electrical behaviour of the SWCNTs. The results showed that impregnating a SWCNT network with a polymer is not the only factor that affects the film resistance; air exposure, temperature, physical and chemical properties of the individual polymer components, and also the formation of a polymeric network, can all have an influence on the macroscopic electrical properties of the initial SWCNT network. These results emphasize the importance of understanding the effects that each of the components can have on each other before trying to prepare an efficient polymer composite material. PMID:25430670

  15. TREATMENT OF STORMWATER BY NATURAL ORGANIC MATERIALS

    EPA Science Inventory

    The overall objective of this study was to evaluate the feasibility of using low-cost natural filter materials for stormwater (SW) treatment. Generic mulch, pine bark mulch, and processed jute were evaluated for metal and organic pollutant removal from actual SW samples collected...

  16. Some strength properties of graphite-zirconium carbide composite materials

    Microsoft Academic Search

    V. S. Dergunova; A. N. Shurshakov; G. D. Posos'eva; L. N. Lutsenko

    1972-01-01

    1.Some factors influencing the strength of composite materials were examined.2.A study was made of the strength properties of graphite-zirconium carbide and graphite-zirconium carbide-zirconium composite materials having varying structures and compositions. It was found that, at 2500‡C, the tensile strength of TsG-25 type composite material is 30% higher than that of dense VPP constructional graphite.3.It was established that, by varying the

  17. Method for preparing dielectric composite materials

    DOEpatents

    Lauf, Robert J.; Anderson, Kimberly K.; Montgomery, Frederick C.; Collins, Jack L.; Felten, John J.

    2004-11-23

    The invention allows the fabrication of small, dense beads of dielectric materials with selected compositions, which are incorporated into a polymeric matrix for use in capacitors, filters, and the like. A porous, generally spherical bead of hydrous metal oxide containing titanium or zirconium is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead may be washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) at elevated temperature and pressure to convert the bead into a mixed hydrous titanium- or zirconium-alkaline earth oxide while retaining the generally spherical shape. Alternatively, the gel bead may be made by coprecipitation. This mixed oxide bead is then washed, dried and calcined to produce the desired (BaTiO.sub.3, PbTiO.sub.3, SrZrO.sub.3) structure. The sintered beads are incorporated into a selected polymer matrix. The resulting dielectric composite material may be electrically "poled" if desired.

  18. Piezoelectric Nanoparticle-Polymer Composite Materials

    NASA Astrophysics Data System (ADS)

    McCall, William Ray

    Herein we demonstrate that efficient piezoelectric nanoparticle-polymer composite materials can be synthesized and fabricated into complex microstructures using sugar-templating methods or optical printing techniques. Stretchable foams with excellent tunable piezoelectric properties are created by incorporating sugar grains directly into polydimethylsiloxane (PDMS) mixtures containing barium titanate (BaTiO3 -- BTO) nanoparticles and carbon nanotubes (CNTs), followed by removal of the sugar after polymer curing. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio and the electrical performance of the foams showed a direct relationship between porosity and the piezoelectric outputs. User defined 2D and 3D optically printed piezoelectric microstructures are also fabricated by incorporating BTO nanoparticles into photoliable polymer solutions such as polyethylene glycol diacrylate (PEGDA) and exposing to digital optical masks that can be dynamically altered. Mechanical-to-electrical conversion efficiency of the optically printed composite is enhanced by chemically altering the surface of the BTO nanoparticles with acrylate groups which form direct covalent linkages with the polymer matrix under light exposure. Both of these novel materials should find exciting uses in a variety of applications including energy scavenging platforms, nano- and microelectromechanical systems (NEMS/MEMS), sensors, and acoustic actuators.

  19. Wetting, superhydrophobicity, and icephobicity in biomimetic composite materials

    NASA Astrophysics Data System (ADS)

    Hejazi, Vahid

    Recent developments in nano- and bio-technology require new materials. Among these new classes of materials which have emerged in the recent years are biomimetic materials, which mimic structure and properties of materials found in living nature. There are a large number of biological objects including bacteria, animals and plants with properties of interest for engineers. Among these properties is the ability of the lotus leaf and other natural materials to repel water, which has inspired researchers to prepare similar surfaces. The Lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. The range of actual and potential applications of superhydrophobic surfaces is diverse including optical, building and architecture, textiles, solar panels, lab-on-a-chip, microfluidic devices, and applications requiring antifouling from biological and organic contaminants. In this thesis, in chapter one, we introduce the general concepts and definitions regarding the wetting properties of the surfaces. In chapter two, we develop novel models and conduct experiments on wetting of composite materials. To design sustainable superhydrophobic metal matrix composite (MMC) surfaces, we suggest using hydrophobic reinforcement in the bulk of the material, rather than only at its surface. We experimentally study the wetting properties of graphite-reinforced Al- and Cu-based composites and conclude that the Cu-based MMCs have the potential to be used in the future for the applications where the wear-resistant superhydrophobicity is required. In chapter three, we introduce hydrophobic coating at the surface of concrete materials making them waterproof to prevent material failure, because concretes and ceramics cannot stop water from seeping through them and forming cracks. We create water-repellant concretes with CA close to 160o using superhydrophobic coating. In chapter four, experimental data are collected in terms of oleophobicity especially when underwater applications are of interest. We develop models for four-phase rough interface of underwater oleophobicity and develop a novel approach to predict the CA of organic liquid on the rough surfaces immersed in water. We investigate wetting transition on a patterned surface in underwater systems, using a phase field model. We demonstrated that roughening on an immersed solid surface can drive the transition from Wenzel to Cassie-Baxter state. This discovery improves our understanding of underwater systems and their surface interactions during the wetting phenomenon and can be applied for the development of underwater oil-repellent materials which are of interest for various applications in the water industry, and marine devices. In chapter five, we experimentally and theoretically investigate the icephobicity of composite materials. A novel comprehensive definition of icephobicity, broad enough to cover a variety of situations including low adhesion strength, delayed ice crystallization, and bouncing is determined. Wetting behavior and ice adhesion properties of various samples are theoretically and experimentally compared. We conclude superhydrophobic surfaces are not necessarily icephobic. The models are tested against the experimental data to verify the good agreement between them. The models can be used for the design of novel superhydrophobic, oleophobic, omniphobic and icephobic composite materials. Finally we conclude that creating surface micro/nanostructures using mechanical abrasion or chemical etching as well as applying low energy materials are the most simple, inexpensive, and durable techniques to create superhydrophobic, oleophobic, and icephobic materials.

  20. Thermophysical Analysis of High Modulus Composite Materials for Space Vehicles

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Sung

    2009-01-01

    High modulus composite materials are used extensively in aerospace vehicles mainly for the purpose of increasing strength and reducing weight. However, thermal properties have become essential design information with the use of composite materials in the thermal design of spacecraft and spacecraft electronics packages. This is because the localized heat from closely packed devices can lead to functional failure of the aerospace system unless the heat is dissipated. In this study, thermal responses of high modulus advanced materials are considered for aerospace thermal design. The advanced composite material is composed of a continuous high modulus pitch based fiber and epoxy resin. In order to compare this advanced composite material with conventional aerospace composite materials, the thermophysical analysis of both materials was performed. The results include thermal conductivity measurements of composite materials and various thermal analytical techniques with DSC, TGA, TMA and DMA.

  1. Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 19. Leaching Characteristics of Composited Materials from Mine Waste-Rock Piles and Naturally Altered Areas near Questa, New Mexico

    USGS Publications Warehouse

    Smith, Kathleen S.; Hageman, Philip L.; Briggs, Paul H.; Sutley, Stephen J.; McCleskey, R. Blaine; Livo, K. Eric; Verplanck, Philip L.; Adams, Monique G.; Gemery-Hill, Pamela A.

    2007-01-01

    The goal of this study is to compare and contrast the leachability of metals and the acidity from individual mine waste-rock piles and natural erosional scars in the study area near Questa, New Mexico. Surficial multi-increment (composite) samples less than 2 millimeters in diameter from five waste-rock piles, nine erosional-scar areas, a less-altered site, and a tailings slurry-pipe sample were analyzed for bulk chemistry and mineralogy and subjected to two back-to-back leaching procedures. The first leaching procedure, the U.S. Geological Survey Field Leach Test (FLT), is a short-duration leach (5-minute shaking and 10-minute settling) and is intended to leach readily soluble materials. The FLT was immediately followed by an 18-hour, end-over-end rotation leaching procedure. Comparison of results from the back-to-back leaching procedures can provide information about reactions that may take place upon migration of leachates through changing geochemical conditions (for example, pH changes), both within the waste-rock and scar materials and away from the source materials. For the scar leachates, the concentrations of leachable metals varied substantially between the scar areas sampled. The scar leachates have low pH (pH 3.2-4.1). Under these low-pH conditions, cationic metals are solubilized and mobile, but anionic species, such as molybdenum, are less soluble and less mobile. Generally, metal concentrations in the waste-rock leachates did not exceed the upper range of those metal concentrations in the erosional-scar leachates. One exception is molybdenum, which is notably higher in the waste-rock leachates compared with the scar leachates. Most of the waste-rock leachates were at least mildly acidic (pH 3.0-6.2). The pH values in the waste-rock leachates span a large pH range that includes some pH-dependent solubility and metal-attenuation reactions. An increase in pH with leaching time and agitation indicates that there is pH-buffering capacity in some of the waste-rock piles. As pH increased in the waste-pile leachates, concentrations of several metals decreased with increasing time and agitation. Similar pH-dependent reactions may take place upon migration of the leachates in the waste-rock piles. Bulk chemistry, mineralogy, and leachate sulfur-isotope data indicate that the Capulin and Sugar Shack West waste-rock piles are compositionally different from the younger Sugar Shack South, Sugar Shack Middle, and Old Sulphur Gulch piles. The Capulin and Sugar Shack West piles have the lowest-pH leachates (pH 3.0-4.1) of the waste-pile samples, and the source material for the Capulin and Sugar Shack West piles appears to be similar to the source material for the erosional-scar areas. Calcite dissolution, in addition to gypsum dissolution, appears to produce the calcium and sulfate concentrations in leachates from the Sugar Shack South, Sugar Shack Middle, and Old Sulphur Gulch piles.

  2. Polymer and Composite Materials Used in Hydrogen Service

    E-print Network

    ), Fuel Cell Technologies Office, to discuss issues associated with polymer and composite materials used1 Polymer and Composite Materials Used in Hydrogen Service MEETING PROCEEDINGS Polymer This report1 describes the results from an information-sharing meeting on the use of polymer and composite

  3. Structural Health Monitoring of Smart Composite Material by Acoustic Emission

    E-print Network

    Paris-Sud XI, Université de

    Structural Health Monitoring of Smart Composite Material by Acoustic Emission S. Masmoudia , A. El fabricated in E-glass fibre/epoxy with a unidirectional play laminate. The composite specimens with sensors composite structures gives the opportunity to develop smart materials for health monitoring systems

  4. The production and application of metal matrix composite materials

    Microsoft Academic Search

    J. W. Kaczmar; K. Pietrzak; W. W?osi?ski

    2000-01-01

    The production methods and properties of metal matrix composite materials reinforced with dispersion particles, platelets, non-continuous (short) and continuous (long) fibres are discussed in this paper. The most widely applied methods for the production of composite materials and composite parts are based on casting techniques such as the squeeze casting of porous ceramic preforms with liquid metal alloys and powder

  5. Optimisation of a multiphase intermetallic metal metal composite material

    E-print Network

    Cambridge, University of

    Optimisation of a multiphase intermetallic metal ± metal composite material J. D. Robson, N to as metal ± metal composites (MeMeCs). In these materials the strong but brittle b and b9 phases act. Duvauchelle, A. Lugan, J. Street, and H. K. D. H. Bhadeshia Metal ± metal composites (MeMeCs) manufactured

  6. Thermal expansion of two-phase texturized composite materials

    Microsoft Academic Search

    R. F. Kozlova; V. B. Rabkin

    1972-01-01

    Theoretical and experimental studies were made of the effects of temperature and composition on the thermal expansion of deformed (texturized) Mo-Cu two-phase composite materials, whose component phases differ markedly in their properties. The anisotropy of thermal expansion of such composite materials was investigated, and it was established that their volume expansion shows very little variation with deformation. It is demonstrated

  7. Review on advanced composite materials boring mechanism and tools

    Microsoft Academic Search

    Runping Shi; Chengyong Wang

    2010-01-01

    With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre\\/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher

  8. Viscoelastic models for polymeric composite materials

    SciTech Connect

    Bardenhagen, S.G.; Harstad, E.N. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Foster, J.C. Jr. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)]|[Wright Laboratory, Armament Directorate, Eglin AFB, Florida 32542 (United States); Maudlin, P.J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1996-05-01

    An improved model of the mechanical properties of the explosive contained in conventional munitions is needed to accurately simulate performance and accident scenarios in weapons storage facilities. A specific class of explosives can be idealized as a mixture of two components: energetic crystals randomly suspended in a polymeric matrix (binder). Strength characteristics of each component material are important in the macroscopic behavior of the composite (explosive). Of interest here is the determination of an appropriate constitutive law for a polyurethane binder material. A Taylor Cylinder impact test, and uniaxial stress tension and compression tests at various strain rates, have been performed on the polyurethane. Evident from time resolved Taylor Cylinder profiles, the material undergoes very large strains ({gt}100{percent}) and yet recovers its initial configuration. A viscoelastic constitutive law is proposed for the polyurethane and was implemented in the finite element, explicit, continuum mechanics code EPIC. The Taylor Cylinder impact experiment was simulated and the results compared with experiment. Modeling improvements are discussed. {copyright} {ital 1996 American Institute of Physics.}

  9. Natural Fibers for Automotive Nonwoven Composites

    Microsoft Academic Search

    Y. Chen; O. Chiparus; L. Sun; I. Negulescu; D. V. Parikh; T. A. Calamari

    2005-01-01

    Two types of nonwoven composites, uniform and sandwich structures, are produced using bagasse, kenaf, ramie, and polypropylene (PP) fibers. The experimental uniform composites include kenaf\\/PP (70\\/30), bagasse\\/PP (50\\/50), and ramie\\/PP (70\\/30). The experimental sandwich composites include kenaf\\/bagasse\\/kenaf and ramie\\/kenaf\\/ramie. A comparative study of these experimental composites is conducted in terms of mechanical properties, thermal properties, and wet properties. Composite tensile

  10. Method for preparing polyolefin composites containing a phase change material

    DOEpatents

    Salyer, Ival O. (Dayton, OH)

    1990-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein. The composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

  11. Reuse of Material Containing Natural Radionuclides - 12444

    SciTech Connect

    Metlyaev, E.G.; Novikova, N.J. [Burnasyan Federal Medical Biophysical Centre, Moscow (Russian Federation)

    2012-07-01

    Disposal of and use of wastes containing natural radioactive material (NORM) or technologically enhanced natural radioactive material (TENORM) with excessive natural background as a building material is very important in the supervision body activity. At the present time, the residents of Octyabrsky village are under resettlement. This village is located just near the Priargunsky mining and chemical combine (Ltd. 'PPGHO'), one of the oldest uranium mines in our country. The vacated wooden houses in the village are demolished and partly used as a building material. To address the issue of potential radiation hazard of the wooden beams originating from demolition of houses in Octyabrsky village, the contents of the natural radionuclides (K-40, Th-232, Ra-226, U- 238) are being determined in samples of the wooden beams of houses. The NORM contents in the wooden house samples are higher, on average, than their content in the reference sample of the fresh wood shavings, but the range of values is rather large. According to the classification of waste containing the natural radionuclides, its evaluation is based on the effective specific activity. At the effective specific activity lower 1.5 kBq/kg and gamma dose rate lower 70 ?R/h, the material is not considered as waste and can be used in building by 1 - 3 classes depending upon A{sub eff} value. At 1.5 kBq/kg < A{sub eff} ? 4 kBq/kg (4 class), the wooden beams might be used for the purpose of the industrial building, if sum of ratios between the radionuclide specific activity and its specific activity of minimum significance is lower than unit. The material classified as the waste containing the natural radionuclides has A{sub eff} higher 1.5 kBq /kg, and its usage for the purpose of house-building and road construction is forbidden. As for the ash classification and its future usage, such usage is unreasonable, because, according to the provided material, more than 50% of ash samples are considered as radioactive waste containing natural radionuclides. All materials originated from demolition of houses in Octyabrsky village are subjected to the obligatory radiation control. The decision to use the wooden beams shall enter into force after agreement with the State Sanitary and Epidemiological Supervision bodies. Conclusions: 1 - The wooden beam originated from the house demolition in Octyabrsky village might be used as the construction material only in case of compliance with the requirements of the regulatory documents, as well as under approval of the authorities responsible for the state sanitary and epidemiological supervision in this area. 2 - The industrial control is introduced to verify the compliance with the current regulations. 3 - The material originated from the house demolition might be used only if such usage does not cause increasing radiation exposure to the public. (authors)

  12. Method of preparing corrosion resistant composite materials

    DOEpatents

    Kaun, Thomas D. (320 Willow St., New Lenox, IL 60451)

    1993-01-01

    Method of manufacture of ceramic materials which require stability in severely-corrosive environment having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These surfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  13. The Nature of Genetic Material Online Module

    NSDL National Science Digital Library

    Center for Educational Outreach and Center for Collaborative and Interactive Technologies * (Baylor College of Medicine; )

    2010-05-27

    The Nature of Genetic Material, a new resource from Baylor College of Medicineâ??s comprehensive website, BioEd Online, is one module of a three-part, interactive Web-based course called Genes, Health and Society. [The course, which explores the rapidly evolving world of genetics and genomics, can be taken free of charge for professional or personal development. Each module stands alone. Educators can work through the modules in sequence or move freely among them.

  14. On the contribution of natural and restored wetlands to changes in the concentration and composition of dissolved organic material in the Sacramento-San Joaquin Delta and San Francisco Estuary.

    NASA Astrophysics Data System (ADS)

    Bergamaschi, B.; Stepanauskas, R.; Fram, M.; Hollibaugh, J.; Fujii, R.

    2002-12-01

    The amount and quality of wetland-derived dissolved organic material (DOM) entering delta and estuary environments remains poorly characterized even though DOM has two roles of societal significance: 1) it supports estuarine foodwebs, commonly habitat for endangered species, and 2) it presents problems when it occurs in drinking water supplies, forming carcinogenic byproducts on treatment. The Sacramento-San Joaquin Delta is a source of drinking water for over 20 million people and contributes 80% of the DOM entering the San Francisco Estuary, nearly doubling the concentration of DOM in the influent river water. The majority of the Delta is composed of below-sea level peat islands maintained in agricultural production by continuous pumping of DOM-rich drain water into Delta channels. Previous studies have shown that changes in the composition of the DOM in water that passes through the Delta are not consistent with addition of peat island drain water, and are more consistent with addition of wetland-derived material, suggesting that wetlands may contribute substantially to DOM export to the Estuary. Although wetlands currently contribute only 14% of the Delta, restoration is planned that would more than double this area, potentially altering DOM quality and content in the Delta and Estuary waters. Over the past several years we have examined the seasonal variation in the quality of DOM added by a variety of wetland types and island drains within the Delta and Estuary. In the current study, thirteen sites were each sampled five times. To date, we have analyzed the samples to determine the content of hydrophobic DOM, characterize the UV absorbance and fluorescence properties, and quantify the susceptibility to biodegradation both before and after photo-exposure. Samples were humic-rich, averaging over 75% hydrophobic content and varying from 74 to 86% with the variation in hydrophobic content between samples corresponding to changes in the optical properties. Samples typically were refractory with respect to biodegradation, with an average of 11% of the DOM susceptible to biodegradation prior to photoexposure, but the range was from 1% to 48%. Following photoexposure, samples were generally more refractory rather than more labile. Wetland DOM was found to react to form more drinking water disinfection byproducts than influent waters, but some wetland types appeared to contribute fewer precursors. Seasonal variation in biodegradation and chemical parameters was much greater than variation among wetland types, and the peak of biodegradeability was not related to the seasonal peak in DOM. This suggests addition of DOM through the Delta is controlled by changes in the nature of the source material rather than changes in efficiency or extent of remineralization.

  15. The Contribution of Natural and Restored Wetlands to Changes in the Concentration and Composition of Dissolved Organic Material in the Sacramento-San Joaquin Delta and San Francisco Estuary

    NASA Astrophysics Data System (ADS)

    Bergamaschi, B. A.; Stepanauskas, R.; Fram, M.; Hollibaugh, J. T.; Fujii, R.

    2002-12-01

    The quantity and quality of wetland-derived dissolved organic material (DOM) entering delta and estuary environments remains poorly characterized, even though DOM has two roles of societal significance: 1) it supports estuarine foodwebs, which commonly are a habitat for endangered species, and 2) it presents problems when it occurs in drinking water supplies, because it forms carcinogenic byproducts when treated. The Sacramento-San Joaquin Delta is a source of drinking water for more than 20 million people and contributes 80% of the DOM entering the San Francisco estuary, nearly doubling the concentration of DOM in the influent river water. The majority of the Delta is composed of below-sea-level peat islands that are maintained in agricultural production by continuous pumping of DOM-rich drain water into Delta channels. Previous studies indicate that changes in DOM composition in water passing through the Delta are not consistent with the addition of peat island drain water, and are more consistent with the addition of wetland-derived material. Therefore, wetlands may contribute substantially to DOM export to the estuary. Although wetlands currently constitute only 14% of the Delta, restoration is planned that would more than double this wetland area, potentially altering DOM quality and content in the Delta and estuary waters. During the past several years, the seasonal variation in the quality of DOM added by a variety of wetland types and island drains within the Delta and estuary has been examined. In this study, 13 sites were sampled 5 times. As of September 2002, the samples have been analyzed to determine the content of hydrophobic DOM, characterize the ultraviolet absorbance and fluorescence properties, and quantify the susceptibility to biodegradation before and after photoexposure. Samples were humic-rich, averaging more than 75% hydrophobic content and varying from 74 to 86%, with the variation in hydrophobic content between samples corresponding to changes in the optical properties. Samples typically were refractory with respect to biodegradation, having an average of 11% of the DOM being susceptible to biodegradation prior to photoexposure, but the range was from 1% to 48%. Following photoexposure, samples generally were more refractory rather than more labile. Wetland DOM reacted to form more drinking water disinfection byproducts than influent waters, but some wetland types seemed to contribute fewer precursors. Seasonal variation in biodegradation and chemical parameters was much greater than variation among wetland types, and the peak of biodegradability was not related to the seasonal peak in DOM. Therefore, the addition of DOM through the Delta is controlled by changes in the nature of the source material rather than changes in efficiency or extent of remineralization.

  16. Fiber optics in composite materials: materials with nerves of glass

    NASA Astrophysics Data System (ADS)

    Measures, Raymond M.

    1990-08-01

    A Fiber Optic BasedSmart Structure wiipossess a structurally integrated optical microsensor system for determining its state. This built-in sensor system should, in real-time, be able to: evaluate the strain or deformation of a structure, monitor if its vibrating or subject to excessive loads, check its temperature and warn of the appearance of any hot spots. In addition a Smart Structure should maintain a vigilant survelliance over its structural integrity. The successful development of Smart StructureTechnolgy could lead to: aircraft that are safer, lighter, more efficient, easier to maintain and to service; pipelines, pressure vessels and storage tanks that constantly monitor their structuralintegrity and immediately issue an alert ifany problem is detected; space platforms that check forpressure leaks, unwanted vibration, excess thermal buildup, and deviation from some preassigned shape.This technology is particularly appropriate for composite materials where internal damage generated by: impacts, manufacturing flaws, excessive loading or fatigue could be detected and assessed. In service monitoring of structural loads, especially in regions like wing roots of aircraft, could be ofconsiderable benefit in helping to avoid structural overdesign and reduce weight. Structurally imbedded optical fibers sensors might also serve to monitor the cure state of composite thermosets during their fabrication and thereby contribute to improved quality control of these products.

  17. Developing polymer composite materials: carbon nanotubes or graphene?

    PubMed

    Sun, Xuemei; Sun, Hao; Li, Houpu; Peng, Huisheng

    2013-10-01

    The formation of composite materials represents an efficient route to improve the performances of polymers and expand their application scopes. Due to the unique structure and remarkable mechanical, electrical, thermal, optical and catalytic properties, carbon nanotube and graphene have been mostly studied as a second phase to produce high performance polymer composites. Although carbon nanotube and graphene share some advantages in both structure and property, they are also different in many aspects including synthesis of composite material, control in composite structure and interaction with polymer molecule. The resulting composite materials are distinguished in property to meet different applications. This review article mainly describes the preparation, structure, property and application of the two families of composite materials with an emphasis on the difference between them. Some general and effective strategies are summarized for the development of polymer composite materials based on carbon nanotube and graphene. PMID:23813859

  18. Tungsten-based composite materials for fusion reactor shields

    Microsoft Academic Search

    E. Greenspan; Y. Karni

    1985-01-01

    Composite tungsten-based materials were recently proposed for the heavy constituent of compact fusion reactor shields. These composite materials will enable the incorporation of tungsten - the most efficient nonfissionable inelastic scattering (as well as good neutron absorbing and very good photon attenuating) material - in the shield in a relatively cheap way and without introducing voids (so as to enable

  19. Composite materials with metallic matrix and ceramic porous filler

    Microsoft Academic Search

    V. I. Bakarinova; V. K. Portnoi

    1995-01-01

    Composite materials with a reduced density reinforced with hollow corundum particles can be of interest as damping and abrasive materials for decreasing the mass of a structure. Methods for mixing powders and their hot pressing are suggested in order to produce such composite materials without fracture of the brittle hollow particles of the filler.

  20. High-porosity powder-fiber composite materials

    Microsoft Academic Search

    A. G. Kostornov; N. E. Fedorova; L. I. Chernyshev

    1983-01-01

    The feasibility is demonstrated of substantially reducing volume changes during the sintering of high-porosity materials by the addition of fibers to a powder mixture. The mechanism of sintering of powder-fiber composites containing more than 25% of fibers is similar to the mechanism of sintering of pure fiber materials. The mechanical properties of permeable composite materials are determined by the fiber

  1. Designing nacre-like materials for simultaneous stiffness, strength and toughness: Optimum materials, composition, microstructure and size

    NASA Astrophysics Data System (ADS)

    Barthelat, Francois

    2014-12-01

    Nacre, bone and spider silk are staggered composites where inclusions of high aspect ratio reinforce a softer matrix. Such staggered composites have emerged through natural selection as the best configuration to produce stiffness, strength and toughness simultaneously. As a result, these remarkable materials are increasingly serving as model for synthetic composites with unusual and attractive performance. While several models have been developed to predict basic properties for biological and bio-inspired staggered composites, the designer is still left to struggle with finding optimum parameters. Unresolved issues include choosing optimum properties for inclusions and matrix, and resolving the contradictory effects of certain design variables. Here we overcome these difficulties with a multi-objective optimization for simultaneous high stiffness, strength and energy absorption in staggered composites. Our optimization scheme includes material properties for inclusions and matrix as design variables. This process reveals new guidelines, for example the staggered microstructure is only advantageous if the tablets are at least five times stronger than the interfaces, and only if high volume concentrations of tablets are used. We finally compile the results into a step-by-step optimization procedure which can be applied for the design of any type of high-performance staggered composite and at any length scale. The procedure produces optimum designs which are consistent with the materials and microstructure of natural nacre, confirming that this natural material is indeed optimized for mechanical performance.

  2. Fracture toughness of natural fibers\\/castor oil polyurethane composites

    Microsoft Academic Search

    R. V. Silva; D. Spinelli; W. W. Bose Filho; S. Claro Neto; G. O. Chierice; J. R. Tarpani

    2006-01-01

    Fracture toughness of natural fibers\\/castor oil polyurethane composites was investigated. The main interest in studying these biomass composites arises from the fact that both fibers and matrix are derived from renewable resources and the formed composite constitute an attempt towards environmental preservation. Sisal and coconut short fibers and woven sisal fabric were used ‘in natura’ and sodium hydroxide treated. The

  3. Potential of Jamaican banana, coconut coir and bagasse fibres as composite materials

    Microsoft Academic Search

    Nilza G. Jústiz-Smith; G. Junior Virgo; Vernon E. Buchanan

    2008-01-01

    This paper presents an evaluation of the alternative use of three Jamaican natural cellulosic fibres for the design and manufacturing of composite materials. The natural cellulosic fibres under investigation were bagasse from sugar cane (saccharum officinarum), banana trunk from the banana plant (family Musacae, genus Musa X para disiaca L), and coconut coir11Coir – a stiff, coarse fibre from the

  4. Shape memory materials and hybrid composites for smart systems: Part II Shape-memory hybrid composites

    Microsoft Academic Search

    Z. G. Wei; R. Sandstrom; S. Miyazaki

    1998-01-01

    By hybridizing or incorporating shape-memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of shape-memory hybrid composites have been designed and manufactured, with

  5. Millimeter-wave imaging of composite materials

    SciTech Connect

    Gopalsami, N.; Bakhtiari, S.; Dieckman, S.L.; Raptis, A.C.; Lepper, M.J.

    1993-09-01

    This work addresses the application and evaluates the potential of mm-wave imaging in the W-band (75-110 GHz) using samples of low-loss dielectric and composite materials with artificial defects. The initial focus is on the measurement of amplitude changes in the back scattered and forward-scattered fields. The c-scan system employs a focused beam antenna to provide spatial resolution of about one wavelength. A plane-wave model is used to calculate the effective reflection (or transmission) coefficient of multilayer test sample geometry. Theoretical analysis is used to optimize the measurement frequency for higher image contrast and to interpret the experimental results. Both reflection and transmission images, based on back scattered and forward-scattered powers, were made with Plexiglas and Kevlar/epoxy samples containing artificially introduced defects such as subsurface voids and disbonds. The results clearly indicate that mm-wave imaging has high potential for non-contact interrogation of low-loss materials.

  6. Possibility of obtaining monolithic composite materials based on niobium carbide

    Microsoft Academic Search

    V. V. Ploshkin; I. Yu. Ul'yanina; V. P. Filonenko

    1984-01-01

    1.Specimens of composite material based on niobium carbide obtained by hydrostatic pressing had minimum porosity compared with specimens obtained by the normal powder metallurgy method.2.Basic phases of the composite material consisting of copper and niobium carbide are uniformly distributed throughout the specimen cross section and they do not react with each other under any conditions.3.The composite material obtained exhibits sufficient

  7. Thermoelectric study of INSB secondary phase based nano composite materials

    NASA Astrophysics Data System (ADS)

    Zhu, Song

    In the past several decades there has been an intensive study in the field of thermoelectric study that is basically materials driven. As the simplest technology applicable in direct heat-electricity energy conversion, thermoelectricity utilizes the Seebeck effect to generate electricity from heat or conversely achieve the solid-state cooling via the Peltier effect. With many technical merits, thermoelectric devices can be used as spot-size generators or distributed refrigerators, however, their applications are restricted by the energy conversion efficiency, which is mainly determined by the figure of merit ZT of the thermoelectric materials that these devices are made of. A higher ZT (ZT=alpha2*sigma/kappa) entails a larger Seebeck coefficient (alpha), a higher electrical conductivity (sigma) and a lower thermal conductivity (kappa). However, it is challenging to simultaneously optimize these three material parameters because they are adversely correlated. To this end, a promising approach to answer this challenge is nano-compositing or microstructuring at multiple length scales. The numerous grain boundaries in nano-composite allow for significant reduction of lattice thermal conductivity via strong phonon scattering and as well an enhanced Seebeck coefficient via, carrier energy filtering effect. As the same grain boundaries also scatter carriers, a coherent interface between grains is needed to minimize the degradation of carrier mobilities. To this end,in-situ, instead of ex-situ, formation of nano-composite is preferred. It is noteworthy that electrical conductivity can be further enhanced by the injection of high-mobility carriers introduced by the secondary nano-phase. In view of the prevalent use of Antimony (Sb) in thermoelectric materials, Indium Antimonide (InSb) naturally becomes one of the most promising nano-inclusions since it possesses one of the largest carrier mobilities (˜7.8 m 2/V-s) in any semiconductors, while at the same time possesses a reasonably narrow band gap (˜0.17 eV at 300 K). In this dissertation, I experimentally investigate whether InSb could be a "good" nano-secondary phase in two thermoelectric bulk matrix materials, FeSb2 and half-Heusler compounds. In these in situ formed nano-composites, three mechanisms are utilized to decouple the otherwise adversely correlated Seebeck coefficient (alpha), electrical conductivity (sigma), and thermal conductivity (kappa). First, low energy carriers will be filtered out via the carrier energy filtering effect, enhancing the Seebeck coefficient without degrading the power factor (PF= alpha 2sigma). Second, high mobility carriers from the InSb nano-inclusions will be injected to the system to increase the electrical conductivity. Last, the numerous grain boundaries present in nano-composites allow for strong phonon scattering so as to reduce the thermal conductivity. After the initial in situ synthesis of nano-composites with the optimized composition, further nano-structuring processes are applied in the samples of FeSb2 with 0.5% atomic ratio of InSb. The results indicate that not all nano-structures are thermoelectrically favorable, multi-scale microstructures with the length scale comparable with the phonon mean free path are needed to effectively scatter phonons over a wide range of wavelength. In summary, the successful combination of the carrier energy filtering effect, high mobility carrier injection effect, and strong phonon scattering effect in the in situ synthesized FeSb2-InSb and half-Heusler-InSb nano-composites leads to a significantly enhanced ZT. This approach of in situ formation of nano-composites based on InSb secondary nano-phase may also be applied to other thermoelectric materials.

  8. New Micro Structural Design Concept for Polycrystalline Composite Materials

    Microsoft Academic Search

    A. N. RYBJANETS; A. V. NASEDKIN; A. V. TURIK

    2004-01-01

    A new concept of microstructural designing of polymer-free polycrystalline composite materials is offered. The concept based on controllable substitution during composite formation of separate crystallites making a polycrystal by pores, crystallites with other composition and\\/or structure or amorphous substances with preliminary FEM modeling of polycrystalline composite properties. A line of precursor small-scale production technologies and polycrystalline composites with unique and

  9. Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

    Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

  10. Photochromism in composite and hybrid materials based on transition-metal oxides and polyoxometalates

    Microsoft Academic Search

    Tao He; Jiannian Yao

    2006-01-01

    Photochromic materials are attractive and promising for applications in many fields. One subject in this area is to prepare and study the photochromism in composite or hybrid materials based on transition-metal oxides or polyoxometalates. Their properties not depend only on the chemical nature of each component, but also on the interface and synergy between them. Since the charge transfer plays

  11. POLYDIMETHYLSILOXANE-BASED SELF-HEALING COMPOSITE AND COATING MATERIALS

    E-print Network

    Braun, Paul

    POLYDIMETHYLSILOXANE-BASED SELF-HEALING COMPOSITE AND COATING MATERIALS BY SOO HYOUN CHO B-healing polymers by introducing tin catalyzed polycondensation of hydroxyl end- functionalized polydimethylsiloxane

  12. (Proceedings of the 5th Technical Conference on Composite Materials, American Society of Composites,

    E-print Network

    Nairn, John A.

    ]s. The first material system was supplied by DuPont and consisted of AvimidR K Polymer/IM6 graphite fiber(Proceedings of the 5th Technical Conference on Composite Materials, American Society of Composites, East Lansing, Michigan, June 11-14, 1990). Fracture Mechanics Analysis of Composite Microcracking

  13. Natural Cork Agglomerate Employed as an Environmentally Friendly Solution for Quiet Sandwich Composites

    PubMed Central

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades. PMID:22574250

  14. Attaching Strain Gages to Composite Materials

    NASA Technical Reports Server (NTRS)

    Penn, B.; Clemons, J. M.; Ledbetter, F. E., III; White, W.

    1984-01-01

    Polyurethane adhesive bonds strain gages reliably to graphite/epoxy composites. Adhesive easy to apply, used over wide temperature range (ambient to cryogenic), and applied in short time. Tests on gages bonded to composite with adhesive demonstrated reliability of attachment.

  15. Natural materials for nano bio systems

    NASA Astrophysics Data System (ADS)

    Ouchen, Fahima; Yaney, Perry; Joyce, Donna; Williams, Adrienne; Gomez, Eliot; Subramanyam, Guru; Grote, James

    2014-09-01

    Many papers have been published on the properties of deoxyribonucleic acid (DNA) and DNAhexadecyltrimethylammonium chloride (CTMA) and their applications in electronics and photonics. This paper is a review of some of the properties and their related applications for other types of naturally occurring materials, nucleic acid bases or nucleobases which make up the DNA molecules. Nucleobases under investigation included guanine, cytosine, adenine and thymine. Potential applications include electron blocking layers for organic light emitting diodes, gate dielectrics for organic thin film transistors and protective layers for polymer-based capacitors.

  16. Some functional properties of composite material based on scrap tires

    NASA Astrophysics Data System (ADS)

    Plesuma, Renate; Malers, Laimonis

    2013-09-01

    The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

  17. Multifunctional Structural Materials for Monitoring and Vibration Plenary Talk: ASME 3-24 Multifunctional Composite Materials

    E-print Network

    Chung, Deborah D.L.

    Plenary Talk: ASME 3-24 Multifunctional Composite Materials Wednesday, 1-1:30 pmMultifunctional Structural Materials for Monitoring and Vibration Damping. November 14, 2012 Abstract Multifunctional structural materials in the form

  18. Elastoplastic analysis of thermal cycling: layered materials with compositional gradients

    Microsoft Academic Search

    A. E. Giannakopoulos; S. Suresh; M. Finot; M. Olsson

    1995-01-01

    Elastopllastic analyses are presented for the cyclic thermal response in multi-layered materials which comprise layers of fixed compositions of a metal and a ceramic, and a compositionally graded interface. Analytical solutions for the characteristic temperature at which the onset of thermally induced plastic deformation occurs are derived for the layered composite. Solutions for the evolution of curvature and thermal strains,

  19. Controlled intermittent interfacial bond concept for composite materials

    NASA Technical Reports Server (NTRS)

    Marston, T. U.; Atkins, A. G.

    1975-01-01

    Concept will enhance fracture resistance of high-strength filamentary composite without degrading its tensile strength or elastic modulus. Concept provides more economical composite systems, tailored for specific applications, and composite materials with mechanical properties, such as tensile strength, fracture strain, and fracture toughness, that can be optimized.

  20. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  1. Process for fabricating composite material having high thermal conductivity

    DOEpatents

    Colella, Nicholas J. (Livermore, CA); Davidson, Howard L. (San Carlos, CA); Kerns, John A. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA)

    2001-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  2. Characterization and prediction of abrasive wear of powder composite materials

    Microsoft Academic Search

    R. Veinthal; P. Kulu; J. Pirso; H. Käerdi

    2009-01-01

    Composite materials produced by powder metallurgy provide a solution in many engineering applications where materials with high abrasion and erosion resistance are required. The actual wear behaviour of the material is associated with many external factors (particle size, velocity, angularity, etc.) and intrinsic material properties (hardness, toughness, Young modulus, etc.). Hardness and toughness properties of such tribomaterials are highly dependent

  3. Characterization of a High Strain Composite Material I. Maqueda

    E-print Network

    Pellegrino, Sergio

    and developed a high-strain composite material consisting of car- bon fibers embedded in a silicone matrixCharacterization of a High Strain Composite Material I. Maqueda and S. Pellegrino California) to provide elastically foldable connections. In this case the stored strain energy in the tape springs

  4. Pistons and Cylinders Made of Carbon-Carbon Composite Materials

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon---carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.

  5. Pistons and Cylinders Made of Carbon-Carbon Composite Materials

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon-carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.

  6. CFRP\\/titanium hybrid material for improving composite bolted joints

    Microsoft Academic Search

    B. Kolesnikov; L. Herbeck; A. Fink

    2008-01-01

    The structural joining remains an essential challenge for the development of composite aerospace structures: every structural interconnection means a disturbance of an optimized structure resulting in an increase in overall structural weight. The lightweight potential of advanced, high-performance fiber composite materials is affected more strongly by mechanical fastening techniques than by conventional metallic materials due to the low shear and

  7. Industry technology assessment of graphite-polymide composite materials. [conferences

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An assessment of the current state of the art and the future prospects for graphite polyimide composite material technology is presented. Presentations and discussions given at a minisymposium of major issues on the present and future use, availability, processing, manufacturing, and testing of graphite polyimide composite materials are summarized.

  8. Intelligent signal processing for damage detection in composite materials

    Microsoft Academic Search

    W. J. Staszewski

    2002-01-01

    Signal processing is an important element of any structural health monitoring system. The paper addresses the importance of intelligent signal processing for damage identification in composite materials. After an initial discussion as to what constitutes the overall signal processing, a number of examples of damage detection in composite materials are presented for illustration. These include: data denoising techniques, feature extraction

  9. Research on damage detection of composite materials based on RBFNN

    Microsoft Academic Search

    Dong Xiaoma; Sun Qingzhen

    2010-01-01

    A dynamic method based on hybrid algorithm RBFNN for damage identification of composite materials was proposed. By using wavelet series, the features of signals were extracted and input to hybrid algorithm RBFNN for training the network and identifying the damages. Finally, the experiment results show that this method can exactly identify the faults of composite materials.

  10. Damage detection in composite materials using Lamb wave methods

    NASA Astrophysics Data System (ADS)

    Kessler, Seth S.; Spearing, S. Mark; Soutis, Constantinos

    2002-04-01

    Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Linear wave scans were performed on narrow laminated specimens and sandwich beams with various cores by monitoring the transmitted waves with piezoceramic sensors. Optimal actuator and sensor configurations were devised through experimentation, and various types of driving signal were explored. These experiments provided a procedure capable of easily and accurately determining the time of flight of a Lamb wave pulse between an actuator and sensor. Lamb wave techniques provide more information about damage presence and severity than previously tested methods (frequency response techniques), and provide the possibility of determining damage location due to their local response nature. These methods may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.

  11. Conducting polyaniline composite: a reusable sensor material for aqueous ammonia

    Microsoft Academic Search

    Sarswati Koul; R Chandra; S. K Dhawan

    2001-01-01

    The present paper reports about polyaniline–(acrylonitrile–butadiene–styrene) composite film as a sensor material for aqueous ammonia. The resistance change of the composite film on exposure to different concentrations of aqueous ammonia shows its utility as a sensor material. The composite film on exposure to 10?4 and 10?5N aqueous ammonia shows a well-defined response behaviour and this aspect has been utilized in

  12. NASA's Reusable Launch Vehicle Technologies: A Composite Materials Overview

    NASA Technical Reports Server (NTRS)

    Clinton, R. G., Jr.; Cook, Steve; Effinger, Mike; Smith, Dennis; Swint, Shayne

    1999-01-01

    A materials overview of the NASA's Earth-to-Orbit Space Transportation Program is presented. The topics discussed are: Earth-to-Orbit Goals and Challenges; Space Transportation Program Structure; Generations of Reusable Launch Vehicles; Space Transportation Derived Requirements; X 34 Demonstrator; Fastrac Engine System; Airframe Systems; Propulsion Systems; Cryotank Structures; Advanced Materials, Fabrication, Manufacturing, & Assembly; Hot and Cooled Airframe Structures; Ceramic Matrix Composites; Ultra-High Temp Polymer Matrix Composites; Metal Matrix Composites; and PMC Lines Ducts and Valves.

  13. Chromatographic behavior of silica-polymer composite molecularly imprinted materials.

    PubMed

    Tóth, B; László, K; Horvai, G

    2005-12-23

    Molecularly imprinted polymers (MIP) have recently been prepared inside the pores of silica based HPLC packing materials. Detailed physical and chromatographic characterization of such a silica-MIP composite material is presented. The chromatographic peak shape obtained with the uniformly sized spherical silica-MIP composite is mainly determined by the nonlinear adsorption isotherm. Comparison of the composite with the conventional sieved and grinded bulk MIP is therefore based on the nonlinear isotherm and not on retention factors and plate numbers. PMID:16188268

  14. Modeling and simulation of manufacturing processes of advanced composite materials

    NASA Astrophysics Data System (ADS)

    Lee, Woo I.; Springer, George S.

    Models for autoclave curing of thermosetting matrix composites are briefly described along with models of manufacturing process models for thermoplastic matrix composites. These models can be used to obtain optimum cure cycles of composite materials. They are particularly useful since the cure cycle must be modified to account for the effect of internal heat generation at the thickness of composite laminate changes. They can be indispensable tools in finding appropriate rules for optimum cure cycles via expert systems.

  15. Advances in thermoplastic matrix composite materials

    SciTech Connect

    Newaz, G.M.

    1989-01-01

    Accounts are given of the development status of thermoplastic composite processing methods, as well as their current thermal and mechanical behavior and delamination properties. Attention is given to the thermoplastic coating of carbon fibers, pultrusion-process modeling, the high temperature behavior of graphite/PEEK, the thermal conductivity of composites for electronic packaging, a FEM analysis of mode I and II thermoplastic-matrix specimens, and reinforcements' resin-impregnation behavior during thermoplastic composite manufacture. Also discussed are the mechanical properties of carbon fiber/PEEK for structural applications, moisture-content mechanical property effects in PPS-matrix composites, the interlaminar fracture toughness of thermoplastic composites, and thermoplastic composite delamination growth under elevated temperature cyclic loading.

  16. Environmental effects on composite materials. Volume 3

    SciTech Connect

    Springer, G.S.

    1988-01-01

    The present collection of papers, each of which has previously been abstracted in International Aerospace Abstracts, discusses the accelerated environmental testing of composites, moisture solubility and diffusion in epoxy and epoxy-glass composites, the influence of internal and external factors affecting moisture absorption in polymer composites, long-tern moisture absorption in graphite/epoxy angle-ply laminates, the effect of UV light on Kevlar 49-reinforced composites, and temperature and moisture induced deformation in composite sandwich panels. Also discussed are the orthotropic thermoelastic problem of uniform heat flow distributed by a central crack, the effect of microcracks on composite laminate thermal expansion, the stress analysis of wooden structures exposed to elevated temperatures, and the deflection of plastic beams at elevated temperatures.

  17. Recent progress of smart composite material in HIT

    NASA Astrophysics Data System (ADS)

    Leng, Jinsong; Yu, Kai; Liu, Yanju

    2009-12-01

    Recent progresses of smart composite material in our ongoing research are presented in this paper. In recent years, shape memory polymers (SMPs) and electroactive polymers (EAPs) attract more and more attention in the world. In our researching work, different kinds of reinforcement are embedded into SMPs and EAPs to form smart composite materials, aiming to improve the properties or strengthen the materials. Based on the unique properties of SMP based smart composite materials, primary application in the deployable morphing wing are also studied, which provide meaningful guidance for further researching works in this area.

  18. Recent progress of smart composite material in HIT

    NASA Astrophysics Data System (ADS)

    Leng, Jinsong; Yu, Kai; Liu, Yanju

    2010-03-01

    Recent progresses of smart composite material in our ongoing research are presented in this paper. In recent years, shape memory polymers (SMPs) and electroactive polymers (EAPs) attract more and more attention in the world. In our researching work, different kinds of reinforcement are embedded into SMPs and EAPs to form smart composite materials, aiming to improve the properties or strengthen the materials. Based on the unique properties of SMP based smart composite materials, primary application in the deployable morphing wing are also studied, which provide meaningful guidance for further researching works in this area.

  19. Corrosion inhibiting composition for treating asbestos containing materials

    DOEpatents

    Hartman, Judithann Ruth (Columbia, MD)

    1998-04-21

    A composition for transforming a chrysotile asbestos-containing material into a non-asbestos material is disclosed, wherein the composition comprises water, at least about 30% by weight of an acid component, optionally a source of fluoride ions, and a corrosion inhibiting amount of thiourea, a lower alkylthiourea, a C.sub.8 -C.sub.15 alkylpyridinium halide or mixtures thereof. A method of transforming an asbestos-containing building material, while part of a building structure, into a non-asbestos material by using the present composition also is disclosed.

  20. Composite materials: Fatigue and fracture. Vol. 3

    NASA Technical Reports Server (NTRS)

    O'Brien, T. K. (editor)

    1991-01-01

    The present volume discusses topics in the fields of matrix cracking and delamination, interlaminar fracture toughness, delamination analysis, strength and impact characteristics, and fatigue and fracture behavior. Attention is given to cooling rate effects in carbon-reinforced PEEK, the effect of porosity on flange-web corner strength, mode II delamination in toughened composites, the combined effect of matrix cracking and free edge delamination, and a 3D stress analysis of plain weave composites. Also discussed are the compression behavior of composites, damage-based notched-strength modeling, fatigue failure processes in aligned carbon-epoxy laminates, and the thermomechanical fatigue of a quasi-isotropic metal-matrix composite.

  1. Wear resistance of composite materials. (Latest citations from Engineered Materials abstracts). Published Search

    SciTech Connect

    Not Available

    1994-09-01

    The bibliography contains citations concerning wear resistance of composite materials. References discuss polymer, ceramic and metal composites. Tribological testing and failure analyses are included. (Contains a minimum of 200 citations and includes a subject term index and title list.)

  2. Multilayer composite material and method for evaporative cooling

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2002-01-01

    A multilayer composite material and method for evaporative cooling of a person employs an evaporative cooling liquid that changes phase from a liquid to a gaseous state to absorb thermal energy. The evaporative cooling liquid is absorbed into a superabsorbent material enclosed within the multilayer composite material. The multilayer composite material has a high percentage of the evaporative cooling liquid in the matrix. The cooling effect can be sustained for an extended period of time because of the high percentage of phase change liquid that can be absorbed into the superabsorbent. Such a composite can be used for cooling febrile patients by evaporative cooling as the evaporative cooling liquid in the matrix changes from a liquid to a gaseous state to absorb thermal energy. The composite can be made with a perforated barrier material around the outside to regulate the evaporation rate of the phase change liquid. Alternatively, the composite can be made with an imperveous barrier material or semipermeable membrane on one side to prevent the liquid from contacting the person's skin. The evaporative cooling liquid in the matrix can be recharged by soaking the material in the liquid. The multilayer composite material can be fashioned into blankets, garments and other articles.

  3. Performance of natural-fiber-plastic composites under stress for outdoor applications: Effect of moisture, temperature, and ultraviolet light exposure

    Microsoft Academic Search

    J. L. Lopez; M. Sain; P. Cooper

    2006-01-01

    The effects of moisture, temperature, and ul- traviolet (UV) light on performance of natural-fiber-plastic composites (NFPC) were assessed. We conducted short-term tests in the laboratory and long-term tests under natural exposure and measured changes in mechanical properties and color in samples of the composite. Chemical changes of the composite's materials were measured by X-ray photo- electron spectroscopy to elucidate the

  4. SOFC ANODE MATERIALS Most common SOFC anode materials are Ni-YSZ composites

    E-print Network

    Mease, Kenneth D.

    MATERIALS SOFC ANODE MATERIALS OVERVIEW Most common SOFC anode materials are Ni-YSZ composites for the anode of a reversible SOFC · Develop a novel sol-gel process for synthesis of SYT · Use the novel sol for use in reversible SOFC anodes · Manufacture composite SYT anodes (with LDC, LSGMC) and test them

  5. Functional ceria–salt-composite materials for advanced ITSOFC applications

    Microsoft Academic Search

    Bin Zhu

    2003-01-01

    This paper reports our current material research and development for advanced intermediate temperature (IT, 400–700°C) solid oxide fuel cells (SOFCs). The materials reported in this work are based on ceria–salt-composites, which have super function, e.g. displaying ionic conductivity of 0.01–1Scm?1 in the IT region. They are functional ceramic materials for advanced ITSOFC applications. When these new composites are used as

  6. Polymeric compositions incorporating polyethylene glycol as a phase change material

    Microsoft Academic Search

    Ival O. Salyer; Charles W. Griffen

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal\\/g; the composition is useful in making molded and\\/or coated materials such as flooring, tiles, wall

  7. Automobile leaf springs from composite materials

    Microsoft Academic Search

    H. A. Al-Qureshi

    2001-01-01

    The automobile industry has shown increased interest in the replacement of steel springs with fiberglass reinforced composite leaf springs. Therefore, the aim of this paper is to present a general study on the analysis, design and fabrication of composite springs. From this viewpoint, the suspension spring of a compact car, “a jeep” was selected as a prototype.A single leaf, variable

  8. ADVANCEMENTS IN ENGINEERED COMPOSITE SANDWICH CORE MATERIALS

    Microsoft Academic Search

    Eric J. Lang

    Results are presented for product and design innova tions involving TYCOR ® fiber-reinforced- foam (FRF) core technology for composite sandwich construction. Low-cost FRF core-preforms used with infusion molding processes provide light, stiff composite sandwich panels and structures. Product design innovations were tested that provide more balanced primary (\\

  9. Structure and Properties of Teflon Composites with Natural Diamond Powders

    Microsoft Academic Search

    A. A. Okhlopkova; E. Yu. Shits

    2004-01-01

    The results of experimental investigations of the structure and properties of composites based on polytetrafluorethylene (PTFE) containing natural diamond powders (NDP) of different dispersity are presented. To obtain diamond-containing compositions for antifrictional applications, we used a preliminary mechanical treatment of NDP (40 µm) in a planetary mill. It was stated that the formation of the maximum ordered small-spherulite structure of

  10. Preparation and properties of recycled HDPE\\/natural fiber composites

    Microsoft Academic Search

    Yong Lei; Qinglin Wu; Fei Yao; Yanjun Xu

    2007-01-01

    Composites based on recycled high density polyethylene (RHDPE) and natural fibers were made through melt blending and compression molding. The effects of the fibers (wood and bagasse) and coupling agent type\\/concentration on the composite properties were studied. The use of maleated polyethylene (MAPE), carboxylated polyethylene (CAPE), and titanium-derived mixture (TDM) improved the compatibility between the bagasse fiber and RHDPE, and

  11. Modeling of self-healing composite materials

    Microsoft Academic Search

    Alexander Dementsov

    2008-01-01

    In this thesis modeling approaches have been considered to describe healing process in self-healing materials. These materials can partially restore their mechanical properties as microcracks develop inside the material. The interest in modeling of self-healing materials comes from recent experiments [1] that show possible perspective applications in many fields of industry. Following the idea of bio-materials that can heal its

  12. Nondestructive inspection and evaluation of composite-material flywheels

    SciTech Connect

    Reifsnider, K.L.; Boyd, D.M.; Kulkarni, S.V.

    1982-02-24

    It has been demonstrated that flywheels made from composite materials are capable of storing energy with a significantly higher energy density than those made from conventional metals. Since composite materials are also very durable and inherently safer for such applications, it would appear that they will play a major role in flywheel energy-storage systems. This report addresses the question of how flywheels made from composite materials can be inspected with nondestructive test methods to establish their initial quality and their subsequent integrity during service. A variety of methods is discussed in the context of special requirements for the examination of composite flywheel structures and the results of several example nondestructive evaluations before and after spin testing are presented. Recommendations for general nondestructive testing and evaluation of composite-material flywheels are made.

  13. Flexible composite material with phase change thermal storage

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    1999-01-01

    A highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The composite material can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The composite may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the PCM composite also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  14. Nano composite phase change materials microcapsules

    NASA Astrophysics Data System (ADS)

    Song, Qingwen

    MicroPCMs with nano composite structures (NC-MicroPCMs) have been systematically studied. NC-MicroPCMs were fabricated by the in situ polymerization and addition of silver NPs into core-shell structures. A full factorial experiment was designed, including three factors of core/shell, molar ratio of formaldehyde/melamine and NPs addition. 12 MicroPCMs samples were prepared. The encapsulated efficiency is approximately 80% to 90%. The structural/morphological features of the NC-MicroPCMs were evaluated. The size was in a range of 3.4 mu m to 4.0 mu m. The coarse appearance is attributed to NPs and NPs are distributed on the surface, within the shell and core. The NC-MicroPCMs contain new chemical components and molecular groups, due to the formation of chemical bonds after the pretreatment of NPs. Extra X-ray diffraction peaks of silver were found indicating silver nano-particles were formed into an integral structure with the core/shell structure by means of chemical bonds and physical linkages. Extra functionalities were found, including: (1) enhancement of IR radiation properties; (2) depression of super-cooling, and (3) increase of thermal stabilities. The effects of SERS (Surface Enhanced Raman Spectroscopy) arising from the silver nano-particles were observed. The Raman scattering intensity was magnified more than 100 times. These effects were also exhibited in macroscopic level in the fabric coatings as enhanced IR radiation properties were detected by the "Fabric Infrared Radiation Management Tester" (FRMT). "Degree of Crystallinity" (DOC) was measured and found the three factors have a strong influence on it. DOC is closely related to thermal stability and MicroPCMs with a higher DOC show better temperature resistance. The thermal regulating effects of the MicroPCMs coatings were studied. A "plateau regions" was detected around the temperature of phase change, showing the function of PCMs. Addition of silver nano-particles to the MicroPCMs has a positive influence on it. NC-MicroPCMs with introducing silver nano particles into the MicroPCMs structure, have shown excellent multifunctional thermal properties and thermal stabilities that are far beyond those of the conventional MicroPCMs. The novel NC-MicroPCMs can be used to develop advanced smart materials and products with prosperous and promising applications in a number of industries.

  15. Characterization and performance of a self-healing composite material

    Microsoft Academic Search

    Michael Richard Kessler

    2002-01-01

    The development of a self-healing polymer-matrix composite material that possesses the ability to heal cracks autonomically is described. The system uses a monomer repair agent, dicyclopentadiene (DCPD), which is stored in an epoxy matrix by dispersing microcapsules containing the liquid repair agent throughout the matrix. When the material is damaged, cracks propagate through the material and break open the microcapsules,

  16. Networks of channels for self-healing composite materials

    Microsoft Academic Search

    A. Bejan; S. Lorente; K.-M. Wang

    2006-01-01

    This is a fundamental study of how to vascularize a self-healing composite material so that healing fluid reaches all the crack sites that may occur randomly through the material. The network of channels is built into the material and is filled with pressurized healing fluid. When a crack forms, the pressure drops at the crack site and fluid flows from

  17. Preparation and properties of multifunctional nylon 6 composite material

    Microsoft Academic Search

    Lai Chiu-Chun; Jen Chyi-Wen; Chang Yuh-Shyang; Huang Kuo-Shien

    2011-01-01

    We considered polyamide 6 as a base material for a composite and added improved tourmaline and carbon fiber to manufacture a material that could release negative ions and resist electromagnetic waves. Through Fourier transform infrared spectroscopy and thermogravimetric analyses, we verified that the improved tourmaline could disperse homogeneously in the base material, whose thermal properties improved as the content of

  18. Genetic optimization of two-material composite laminates

    Microsoft Academic Search

    Laurent Grosset; Satchi Venkataraman; Raphael T. Haftka

    This paper describes the optimization of a composite laminate made from two materials. The use of two materials in the laminates design can offer improved designs, as it is possible to combine the desirable properties of the two materials. In this paper, we consider the use of graphite-epox y, which has high stiffness properties, but is expensive, and glass-epoxy, which

  19. Solid freeform fabrication of highly loaded composite materials

    NASA Astrophysics Data System (ADS)

    Souvignier, Chad William

    Composites are known for their unique blend of modulus, strength, and toughness. This study focuses on two types of composites; organic-inorganic hybrids and the mineralization of highly swollen polymer gels. Both of these composite systems mimic the biological process of composite formation, known as biomineralization. Biomineralization allows for the control of the precipitating phase through an interaction with the organic matrix. This allows higher volume fractions of inorganic material than can be achieved by many traditional processing techniques. Solid freeform fabrication is a processing method that builds materials by the sequential addition of thin layers. As long as the material can easily be converted from a liquid to a solid, it should be amenable for this processing technique. Freeform fabrication has three distinctions from traditional processing techniques that may enable the formation of composite materials with improved mechanical properties. These are the sequential addition of layers, which allows a layer by layer influence of chemistry, the ability to form complex geometries, and finally, extrusion freeform fabrication has been shown to align fibers due to the extrusion of the slurry through a needle. Cracking and shrinkage still play a major role in forming solid parts. The use of an open mesh structure in combination with proper materials selection allowed the formation of highly loaded composite materials without cracking. The modulus values of these materials ranged from 0.1 GPa to 6.0 GPa. The mechanical properties of these materials were modeled.

  20. Composite-Material Tanks with Chemically Resistant Liners

    NASA Technical Reports Server (NTRS)

    DeLay, Thomas K.

    2004-01-01

    Lightweight composite-material tanks with chemically resistant liners have been developed for storage of chemically reactive and/or unstable fluids . especially hydrogen peroxide. These tanks are similar, in some respects, to the ones described in gLightweight Composite-Material Tanks for Cryogenic Liquids h (MFS-31379), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 58; however, the present tanks are fabricated by a different procedure and they do not incorporate insulation that would be needed to prevent boil-off of cryogenic fluids. The manufacture of a tank of this type begins with the fabrication of a reusable multisegmented aluminum mandrel in the shape and size of the desired interior volume. One or more segments of the mandrel can be aluminum bosses that will be incorporated into the tank as end fittings. The mandrel is coated with a mold-release material. The mandrel is then heated to a temperature of about 400 F (approximately equal to 200 C) and coated with a thermoplastic liner material to the desired thickness [typically approxiamtely equal to 15 mils (approximately equal to 0.38 mm)] by thermal spraying. In the thermal-spraying process, the liner material in powder form is sprayed and heated to the melting temperature by a propane torch and the molten particles land on the mandrel. The sprayed liner and mandrel are allowed to cool, then the outer surface of the liner is chemically and/or mechanically etched to enhance bonding of a composite overwrap. The etched liner is wrapped with multiple layers of an epoxy resin reinforced with graphite fibers; the wrapping can be done either by manual application of epoxy-impregnated graphite cloth or by winding of epoxy-impregnated filaments. The entire assembly is heated in an autoclave to cure the epoxy. After the curing process, the multisegmented mandrel is disassembled and removed from inside, leaving the finished tank. If the tank is to be used for storing hydrogen peroxide, then the liner material should be fluorinated ethylene/propylene (FEP), and one or more FEP O ring(s) should be used in the aluminum end fitting(s). This choice of materials is dictated by experimental observations that pure aluminum and FEP are the only materials suitable for long-term storage of hydrogen peroxide and that other materials tend to catalyze the decomposition of hydrogen peroxide to oxygen and water. Other thermoplastic liner materials that are suitable for some applications include nylon 6 and polyethylene. The processing temperatures for nylon 6 are lower than those for FEP. Nylon 6 is compatible with propane, natural gas, and other petroleum-based fuels. Polyethylene is compatible with petroleum- based products and can be used for short-term storage of hydrogen peroxide.

  1. Composite material application for liquid rocket engines

    NASA Technical Reports Server (NTRS)

    Heubner, S. W.

    1982-01-01

    With increasing emphasis on improving engine thrust-to-weight ratios to provide improved payload capabilities, weight reductions achievable by the use of composites have become attractive. Of primary significance is the weight reduction offered by composites, although high temperature properties and cost reduction were also considered. The potential for application of composites to components of Earth-to-orbit hydrocarbon engines and orbit-to-orbit LOX/H2 engines was assessed. The components most likely to benefit from the application of composites were identified, as were the critical technology areas where developed would be required. Recommendations were made and a program outlined for the design, fabrication, and demonstration of specific engine components.

  2. Composite materials with integrated embedded sensing networks

    E-print Network

    Schaaf, Kristin Leigh

    2008-01-01

    Beam Interlaminar Shear Strength of G-10CR Glass-Cloth/Epoxyshort-beam shear strength. Glass/epoxy composite materialsepoxy adhesive at ambient laboratory conditions. Property Tensile strength Shear strength

  3. Microthermodynamics analysis of the shape memory effect in composite materials

    SciTech Connect

    Boyd, J.G.; Lagoudas, D.C. [Texas A and M Univ., College Station, TX (United States)

    1994-12-31

    The shape memory effect and pseudoelasticity due to phase transformation in shape memory alloy (SMA) composites is modeled using a two part procedure. First, phenomenological constitutive equations are proposed for the monolithic polycrystalline SMA material. The equations are of the generalized standard material type, in which the response is given by a convex free energy function and a dissipation potential. Second, a micromechanics analysis of a SMA composite material is performed to derive its free energy, transformation strain rate, and Clausius-Clapeyron equation. Specific results are given for a Nitinol SMA fiber/elastomer matrix composite.

  4. Preparation of composite materials in space. Volume 2: Technical report

    NASA Technical Reports Server (NTRS)

    Steurer, W. H.; Kaye, S.

    1973-01-01

    A study to define promising materials, significant processing criteria, and the related processing techniques and apparatus for the preparation of composite materials in space was conducted. The study also established a program for zero gravity experiments and the required developmental efforts. The following composite types were considered: (1) metal-base fiber and particle composites, including cemented compacts, (2) controlled density metals, comprising plain and reinforced metal foams, and (3) unidirectionally solidified eutectic alloys. A program of suborbital and orbital experiments for the 1972 to 1978 time period was established to identify materials, processes, and required experiment equipment.

  5. Advanced composites: Fabrication processes for selected resin matrix materials

    NASA Technical Reports Server (NTRS)

    Welhart, E. K.

    1976-01-01

    This design note is based on present state of the art for epoxy and polyimide matrix composite fabrication technology. Boron/epoxy and polyimide and graphite/epoxy and polyimide structural parts can be successfully fabricated. Fabrication cycles for polyimide matrix composites have been shortened to near epoxy cycle times. Nondestructive testing has proven useful in detecting defects and anomalies in composite structure elements. Fabrication methods and tooling materials are discussed along with the advantages and disadvantages of different tooling materials. Types of honeycomb core, material costs and fabrication methods are shown in table form for comparison. Fabrication limits based on tooling size, pressure capabilities and various machining operations are also discussed.

  6. The atomic weight and isotopic composition of boron and their variation in nature

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The boron isotopic composition and atomic weight value and their variation in nature are reviewed. Questions are raised about the previously recommended value and the uncertainty for the atomic weight. The problem of what constitutes an acceptable range for normal material and what should then be considered geologically exceptional is discussed. Recent measurements make some previous decisions in need of re-evaluation.

  7. Introduction to naturally occurring radioactive material

    SciTech Connect

    Egidi, P.

    1997-08-01

    Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels of radiation and radioactivity. But some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Other activities, such as flying at high altitudes, expose us to elevated levels of NORM. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose-based standards. So when is TENORM a problem? Where is it a problem? That depends on when, where, and whom you talk to! We will start by reviewing background radioactivity, then we will proceed to the geology, mobility, and variability of these radionuclides. We will then review some of the industrial sectors affected by TENORM, followed by a brief discussion on regulatory aspects of the issue.

  8. Comparison of self repair in various composite matrix materials

    NASA Astrophysics Data System (ADS)

    Dry, Carolyn

    2014-04-01

    In a comparison of self repair in graphite composites (for airplane applications) versus epoxy and vinyl ester composites (for building structures or walls) 1 the type of damage that the fiber/matrix is prone to experience is a prime factor in determining which materials self repair well and 2 the flow of energy during damage determines what kinds of damage that can be self repaired well. 1) In brittle composites, repair was successful throughout the composite due to matrix cracking which allowed for optimum chemical flow, whereas in toughened composites that did not crack, the repair chemical flows into a few layers of the composite. 2) If the damage energy is stopped by the composite and goes laterally, it causes delamination which will be repaired; however if the damage energy goes through the composite as with a puncture, then there will be limited delamination, less chemical release and less self repair.

  9. Impact of gas composition on natural gas storage by adsorption

    Microsoft Academic Search

    José P. B. Mota

    1999-01-01

    Adsorption storage is the most promising low-pressure alternative for storing natural gas, but some operational difficulties hinder the success of this technology. From a modeling perspective, this article addresses the impact of gas composition on the cyclic behavior of adsorptive natural gas storage systems. The cyclic operation of an onboard storage reservoir is modeled as a series of consecutive two-step

  10. Natural Language Processing with Distributional Compositional Models Jean Maillard

    E-print Network

    Natural Language Processing with Distributional Compositional Models Jean Maillard Supervised by: Dr Stephen Clark, Computer Laboratory, University of Cambridge Natural Language Processing know a word by the company it keeps". The principle is that the meaning of a word can be captured

  11. Effects of graphite-epoxy composite materials on the corrosion behavior of aircraft alloys. Phase report

    Microsoft Academic Search

    P. Fischer; J. De Luccia

    1975-01-01

    The electrochemical approach was used to show the nature of the galvanic corrosion when graphite-epoxy composite materials are coupled to aluminum and titanium alloys. An open circuit potential difference of one volt was obtained in 3.5% NaCl solution between the composite and 7075-T6, 7075-T651 and 5052-H38 alloys. This potential difference provides a driving force for corrosion and is cause for

  12. Friction Composites: Traditions and New Solutions (Review). Part 2. Composite Materials

    Microsoft Academic Search

    Viktor M. Kryachek

    2005-01-01

    Success in research, production and testing of composite materials is considered. Fields of their practical application are discussed. New methods for forming friction components and coatings on them are analyzed. It is shown that the main research in the field of friction materials is concentrated on composites with metal, ceramic, and carbon matrices.

  13. Nature of branching in disordered materials

    Microsoft Academic Search

    Amit S. Kulkarni

    2007-01-01

    The phenomenon of structural branching is ubiquitous in a wide array of materials such as polymers, ceramic aggregates, networks and gels. These materials with structural branching are a unique class of disordered materials and often display complex architectures. Branching has a strong influence over the structure-property relationships of these materials. Despite the generic importance across a wide spectrum of materials,

  14. Novel Synthetic Material Mimicking Mechanisms from Natural Nacre

    Microsoft Academic Search

    Allison Juster; Felix Latourte; Horacio D. Espinosa

    \\u000a The biomimetics field has become very popular as Mother Nature creates materials with superior strength and toughness out\\u000a of relatively weak material constituents. This concept is attractive because current synthetic materials have yet to achieve\\u000a this level of performance from the same weak material constituents. Nacre, from Red Abalone shells, is among the natural materials\\u000a exhibiting outstanding toughness, while being

  15. Composite materials for thermal energy storage: enhancing performance through microstructures.

    PubMed

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-05-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. PMID:24591286

  16. Health, safety and environmental requirements for composite materials

    NASA Technical Reports Server (NTRS)

    Hazer, Kathleen A.

    1994-01-01

    The health, safety and environmental requirements for the production of composite materials are discussed. The areas covered include: (1) chemical identification for each chemical; (2) toxicology; (3) industrial hygiene; (4) fire and safety; (5) environmental aspects; and (6) medical concerns.

  17. Composite materials with self-contained wireless sensing networks

    NASA Astrophysics Data System (ADS)

    Schaaf, Kristin; Kim, Robert; Nemat-Nasser, Sia

    2010-04-01

    The increasing demand for in-service structural health monitoring, particularly in the aircraft industry, has stimulated efforts to integrate self sensing capabilities into materials and structures. This work presents efforts to develop structural composite materials which include networks of sensors with decision-making capabilities that extend the functionality of the composite materials to be information-aware. Composite panels are outfitted with networks of self-contained wireless sensor modules which can detect damage in composite materials via active nondestructive testing techniques. The wireless sensor modules will communicate with one another and with a central processing unit to convey the sensor data while also maintaining robustness and the ability to self-reconfigure in the event that a module fails. Ultimately, this research seeks to create an idealized network that is compact in size, cost efficient, and optimized for low power consumption while providing a sufficient data transfer rate to a local host.

  18. Damage detection in composite materials by FBGs

    NASA Astrophysics Data System (ADS)

    Menendez, Jose M.; Munoz, Pedro; Pintado, J. M.; Guemes, Alfredo

    2004-06-01

    Embedded fiber Bragg gratings (FBGs) are sensitive to changes of near strain fields in a composite host monolithic structure, typical of aircraft airframes. FBGs have been embedded in different configurations (a typical position is the skin -- stiffener interface in a monolithic structure) for detecting events associated to damage occurrence. Thus, it is possible to think in FBGs not only as strain sensors, in a classical load monitoring configuration, but as a part of a structural health monitoring (SHM) system in composite structures dimensioned following damage tolerance criteria.

  19. Thermal expansion behaviour of thermoplastic composite materials

    SciTech Connect

    Barnes, J.A.; Simms, I.J.; Farrow, G.J.; Jackson, D.; Wostenholm, G. (Imperial Chemical Industries, PLC, Materials Research Centre, Wilton (England) Salford Univ. (England))

    1990-01-01

    The thermal expansion behavior of a number of commercially available and experimental continuous fiber-reinforced PEEK composites is assessed. The thermal expansion characteristics of Hercules AS4 reinforced PEEK (APC-2/AS4, ICI Fiberite) are reported in some detail, and it is shown that behavior is both reasonable and predictable. Further, it is found that repeated thermal cycling between -160 C and +120 C has no effect on the behavior of unidirectional laminates, and that the inherent characteristics of the composite are likely to promote such insensitivity. 16 refs.

  20. Damage detection in sandwich composite materials using laser vibrometry in conjunction with nonlinear system identification

    Microsoft Academic Search

    Sara Underwood; David Koester; Douglas E. Adams

    2009-01-01

    Fiberglass sandwich panels are tested to study a vibration-based method for locating damage in composite materials. This method does not rely on a direct comparison of the natural frequencies, mode shapes, or residues in the forced vibration response data. Specifically, a nonlinear system identification based method for damage detection is sought that reduces the sensitivity of damage detection results to

  1. Fiber-matrix interfacial adhesion in natural fiber composites

    NASA Astrophysics Data System (ADS)

    Tran, L. Q. N.; Yuan, X. W.; Bhattacharyya, D.; Fuentes, C.; van Vuure, A. W.; Verpoest, I.

    2015-04-01

    The interface between natural fibers and thermoplastic matrices is studied, in which fiber-matrix wetting analysis and interfacial adhesion are investigated to obtain a systematic understanding of the interface. In wetting analysis, the surface energies of the fibers and the matrices are estimated using their contact angles in test liquids. Work of adhesion is calculated for each composite system. For the interface tests, transverse three point bending tests (3PBT) on unidirectional (UD) composites are performed to measure interfacial strength. X-ray photoelectron spectroscopy (XPS) characterization on the fibers is also carried out to obtain more information about the surface chemistry of the fibers. UD composites are examined to explore the correlation between the fiber-matrix interface and the final properties of the composites. The results suggest that the higher interfacial adhesion of the treated fiber composites compared to untreated fiber composites can be attributed to higher fiber-matrix physico-chemical interaction corresponding with the work of adhesion.

  2. Universal composition–structure–property maps for natural and biomimetic platelet–matrix composites and stacked heterostructures

    NASA Astrophysics Data System (ADS)

    Sakhavand, Navid; Shahsavari, Rouzbeh

    2015-03-01

    Many natural and biomimetic platelet–matrix composites—such as nacre, silk, and clay-polymer—exhibit a remarkable balance of strength, toughness and/or stiffness, which call for a universal measure to quantify this outstanding feature given the structure and material characteristics of the constituents. Analogously, there is an urgent need to quantify the mechanics of emerging electronic and photonic systems such as stacked heterostructures. Here we report the development of a unified framework to construct universal composition–structure–property diagrams that decode the interplay between various geometries and inherent material features in both platelet–matrix composites and stacked heterostructures. We study the effects of elastic and elastic-perfectly plastic matrices, overlap offset ratio and the competing mechanisms of platelet versus matrix failures. Validated by several 3D-printed specimens and a wide range of natural and synthetic materials across scales, the proposed universally valid diagrams have important implications for science-based engineering of numerous platelet–matrix composites and stacked heterostructures.

  3. Universal composition-structure-property maps for natural and biomimetic platelet-matrix composites and stacked heterostructures.

    PubMed

    Sakhavand, Navid; Shahsavari, Rouzbeh

    2015-01-01

    Many natural and biomimetic platelet-matrix composites--such as nacre, silk, and clay-polymer-exhibit a remarkable balance of strength, toughness and/or stiffness, which call for a universal measure to quantify this outstanding feature given the structure and material characteristics of the constituents. Analogously, there is an urgent need to quantify the mechanics of emerging electronic and photonic systems such as stacked heterostructures. Here we report the development of a unified framework to construct universal composition-structure-property diagrams that decode the interplay between various geometries and inherent material features in both platelet-matrix composites and stacked heterostructures. We study the effects of elastic and elastic-perfectly plastic matrices, overlap offset ratio and the competing mechanisms of platelet versus matrix failures. Validated by several 3D-printed specimens and a wide range of natural and synthetic materials across scales, the proposed universally valid diagrams have important implications for science-based engineering of numerous platelet-matrix composites and stacked heterostructures. PMID:25774944

  4. Review of low-velocity impact properties of composite materials

    Microsoft Academic Search

    M. O. W. Richardson; M. J. Wisheart

    1996-01-01

    This paper is a review of low-velocity impact responses of composite materials. First the term ‘low-velocity impact’ is defined and major impact-induced damage modes are described from onset of damage through to final failure. Then, the effects of the composite's constituents on impact properties are discussed and post-impact performance is assessed in terms of residual strength.

  5. Polymer?Nanoparticle Composites: Preparative Methods and Electronically Active Materials

    Microsoft Academic Search

    P. K. Sudeep; Todd Emrick

    2007-01-01

    The field of nanoparticle?polymer composites is attractive from the standpoint of integrating the key features of both polymers and nanoparticles into hybrid or composite materials. Nanocomposites geared towards electronic and photophysical targets comprise an intriguing subset of the field, and benefit from interdisciplinary efforts in nanoparticle and polymer synthesis, along with methodology that provides the dispersion, orientation, and\\/or the assembly

  6. Damage detection in composite materials using identification techniques

    Microsoft Academic Search

    F. J. Soeiro; P. Hajela

    1993-01-01

    The present paper describes an approach for damage detection in composite structures that has its basis in methods of system identification. Response of a damaged structure differs from predictions obtained from a mathematical model of the original structure, where such a model is typically a finite-element representation of the structure. In the present work, which deals with composite materials, two

  7. Tribological Properties of Composite Materials Based on Refractory Titanium Compounds

    Microsoft Academic Search

    T. M. Evtushok; O. N. Grigor'ev; A. D. Kostenko; G. L. Zhunkovskii; V. A. Kotenko; P. V. Mazur

    2005-01-01

    The tribological properties have been examined for composite materials based on binary titanium-chromium boride and titanium nitride under conditions of dry friction over a wide speed range (1–25 m\\/sec). The materials have good tribological properties, which exceed by almost an order of magnitude those of known materials. Specifications are formulated for materials promising for high-speed friction units. A necessary condition

  8. Bone substitute material on the basis of natural components

    NASA Astrophysics Data System (ADS)

    Melnikova, S.; Zelichenko, E.; Zenin, B.; Guzeev, V.; Gurova, O.

    2014-10-01

    The creation of regenerative materials remains a problem for rehabilitation medicine, but the obtaining of initial substances that can cause bone tissue regeneration, possessing biological activity and creation on their basis of composite materials with specified physical and mechanical characteristics is an important scientific problem. This paper presents the investigation of physical-chemical and biological properties of bioresorbable composite material that can restore their own bone tissue of the body.

  9. Resistance fail strain gage technology as applied to composite materials

    NASA Technical Reports Server (NTRS)

    Tuttle, M. E.; Brinson, H. F.

    1985-01-01

    Existing strain gage technologies as applied to orthotropic composite materials are reviewed. The bonding procedures, transverse sensitivity effects, errors due to gage misalignment, and temperature compensation methods are addressed. Numerical examples are included where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain measurement errors.

  10. Corrosion of composite materials subjected to periodic wetting

    Microsoft Academic Search

    H. H. Maksymovych; O. V. Filipovs'kyi; V. S. Baranets'kyi; S. M. Kudlak

    1996-01-01

    To demonstrate the danger of corrosion processes induced in composite materials by periodic wetting in corrosive media, we\\u000a develop a special software-controlled compact installation for accelerated corrosion tests. By using this installation, we\\u000a study the corrosion resistance of composite materials based on M40 aluminum alloy and reinforced with boron fibers. It is\\u000a determined both by the state of the surface

  11. Structural stability of reinforced nickel-base composite materials

    Microsoft Academic Search

    I. N. Frantsevich; D. M. Karpinos; V. A. Bespyatyi

    1969-01-01

    1.Stress-rupture tests were carried out on reinforced specimens of composite materials consisting of an alloyed matrix and tungsten or molybdenum fibers at temperatures of 900 and 950°C.2.A technique is proposed for studying the character of rupture of composite materials, consisting in dissolving the specimen matrix after testing and grading the fiber fragments by length. The most frequently encountered fiber-fragment length

  12. Introduction to Composite Materials for Engineers and Technicians

    NSDL National Science Digital Library

    Stuart, William Joseph

    This learning module will help instructors explain composite materials specifically for engineers and technicians. Students will learn the structure and advantages of composite materials as well as the basic processing procedures involved in their creation. It will serve as a one-lecture introduction and would be appropriate for students at the high school or college level. This document will serve as a framework for instructors and may be downloaded in PDF format.

  13. Composite Materials for Radiation Shielding During Deep Space Missions

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Watts, J.; Adams, J. H.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during deep space missions is essential to human health and sensitive instrument survivability. Given the fabrication constraints of space transportation vehicles protective shielding is, consequently, a complicated materials issue. These concerns are presented and considered in view of some novel composite materials being developed/suggested for GCR shielding applications. Advantages and disadvantages of the composites will be discussed as well as the need for coordinated testing/evaluation and modeling efforts.

  14. An analysis of delamination in composite material notched tensile beams

    E-print Network

    Tangirala, Prema Kumar

    1991-01-01

    AN ANALYSIS OF DELAMINATION IN COMPOSITE MATERIAL NOTCHED TENSILE BEAMS A Thesis by PREMA KUMAR TANGIRALA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1991 Major Subject: Mechanical Engineering AN ANALYSIS OF DELAMINATION IN COMPOSITE MATERIAL NOTCHED TENSILE BEAMS A Thesis by PREMA KUMAR TANGIRALA Approved as to style and content by: H A. Hogan (Chair of Committee...

  15. Theories of failure of filament wound-case composite materials

    SciTech Connect

    Lewis, G.

    1986-07-01

    The appropriate failure criterion for composite materials is perhaps one of the most contentious issues in the field. A critical review of the main theories is presented. It is suggested that the tensor polynominal theory, with a modification for normal stress interaction, be adopted. The failure envelopes for the composite materials being studied for the construction of the casing of the solid rocket booster motor of the US Space Shuttle are obtained using this theory. 14 references, 3 figures, 3 tables.

  16. New composite thermoelectric materials for energy harvesting applications

    Microsoft Academic Search

    M. S. Dresselhaus; G. Chen; Z. F. Ren; G. Dresselhaus; A. Henry; J.-P. Fleurial

    2009-01-01

    The concept of using nanostructured composite materials to enhance the dimensionless thermoelectric figure of merit ZT relative\\u000a to that for their counterpart homogeneous alloyed bulk crystalline materials of similar chemical composition is presented\\u000a in general terms. Specific applications are made to the Si-Ge and Bi2-?xSbxTe3 systems for use in high-temperature power generation and cooling applications. The scientific advantages of the

  17. Damage detection in composite materials using Lamb wave methods

    Microsoft Academic Search

    Seth S. Kessler; S. Mark Spearing; Constantinos Soutis

    2002-01-01

    Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite\\/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and

  18. Statistical analysis and interpolation of compositional data in materials science.

    PubMed

    Pesenson, Misha Z; Suram, Santosh K; Gregoire, John M

    2015-02-01

    Compositional data are ubiquitous in chemistry and materials science: analysis of elements in multicomponent systems, combinatorial problems, etc., lead to data that are non-negative and sum to a constant (for example, atomic concentrations). The constant sum constraint restricts the sampling space to a simplex instead of the usual Euclidean space. Since statistical measures such as mean and standard deviation are defined for the Euclidean space, traditional correlation studies, multivariate analysis, and hypothesis testing may lead to erroneous dependencies and incorrect inferences when applied to compositional data. Furthermore, composition measurements that are used for data analytics may not include all of the elements contained in the material; that is, the measurements may be subcompositions of a higher-dimensional parent composition. Physically meaningful statistical analysis must yield results that are invariant under the number of composition elements, requiring the application of specialized statistical tools. We present specifics and subtleties of compositional data processing through discussion of illustrative examples. We introduce basic concepts, terminology, and methods required for the analysis of compositional data and utilize them for the spatial interpolation of composition in a sputtered thin film. The results demonstrate the importance of this mathematical framework for compositional data analysis (CDA) in the fields of materials science and chemistry. PMID:25547365

  19. DISLOCATION MECHANICS ASPECTS OF ENERGETIC MATERIAL COMPOSITES

    Microsoft Academic Search

    R. W. Armstrong

    The dislocation mechanics based properties of solid energetic materials, particularly, of high explosives, are of particular interest in connection with issues of intrinsic chemical stability and with their fast chemical decomposition when employed as propellants or in explosive formulations. The ballistic impact and shock-associated plasticity responses of such materials present great experimental and model challenges for establishment of predictable performances.

  20. A self-healing thermosetting composite material

    Microsoft Academic Search

    S. A. Hayes; F. R. Jones; K. Marshiya; W. Zhang

    2007-01-01

    Strategies for the repair or replacement of thermosetting composite components are essential for their safe operation in many applications. To achieve this, complex repair strategies are often employed, requiring gross manual intervention. This is appropriate for extensive damage, but for minor damage can prove inefficient and not worthwhile given the damage that the repair process often inflicts on the structure.

  1. http://jtc.sagepub.com Composite Materials

    E-print Network

    Agricultural Center, Baton Rouge, LA 70803, USA ABSTRACT: Wood flour (WF) and talc-filled polylactic acid (PLA biodegradable synthetic polymers are aliphatic polyesters such as polylactic acid (PLA), polyglycolic acids (PGA/Talc-filled Polylactic Acid Composites: Effect of Filler Content and Coupling Treatment SUN-YOUNG LEE,1, * IN-AEH KANG,1

  2. Advanced AE Techniques in Composite Materials Research

    NASA Technical Reports Server (NTRS)

    Prosser, William H.

    1996-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been successfully used to evaluate damage mechanisms in laboratory testing of composite coupons. An example is presented in which the initiation of transverse matrix cracking was monitored. In these tests, broad band, high fidelity acoustic sensors were used to detect signals which were then digitized and stored for analysis. Analysis techniques were based on plate mode wave propagation characteristics. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. This technique also allows much more precise source location than conventional, threshold crossing arrival time determination techniques. To apply Modal AE concepts to the interpretation of AE on larger composite specimens or structures, the effects of modal wave propagation over larger distances and through structural complexities must be well characterized and understood. To demonstrate these effects, measurements of the far field, peak amplitude attenuation of the extensional and flexural plate mode components of broad band simulated AE signals in large composite panels are discussed. These measurements demonstrated that the flexural mode attenuation is dominated by dispersion effects. Thus, it is significantly affected by the thickness of the composite plate. Furthermore, the flexural mode attenuation can be significantly larger than that of the extensional mode even though its peak amplitude consists of much lower frequency components.

  3. Damage detection in composite materials by FBGs

    Microsoft Academic Search

    Jose M. Menendez; Pedro Munoz; J. M. Pintado; Alfredo Guemes

    2004-01-01

    Embedded fiber Bragg gratings (FBGs) are sensitive to changes of near strain fields in a composite host monolithic structure, typical of aircraft airframes. FBGs have been embedded in different configurations (a typical position is the skin -- stiffener interface in a monolithic structure) for detecting events associated to damage occurrence. Thus, it is possible to think in FBGs not only

  4. Delamination durability of composite materials for rotorcraft

    NASA Technical Reports Server (NTRS)

    Obrien, T. Kevin

    1988-01-01

    Delamination is the most commonly observed failure mode in composite rotorcraft dynamic components. Although delamination may not cause immediate failure of the composite part, it often precipitates component repair or replacement, which inhibits fleet readiness, and results in increased life cycle costs. A fracture mechanics approach for analyzing, characterizing, and designing against delamination will be outlined. Examples of delamination problems will be illustrated where the strain energy release rate associated with delamination growth was found to be a useful generic parameter, independent of thickness, layup, and delamination source, for characterizing delamination failure. Several analysis techniques for calculating strain energy release rates for delamination from a variety of sources will be outlined. Current efforts to develop ASTM standard test methods for measuring interlaminar fracture toughness and developing delamination failure criteria will be reviewed. A technique for quantifying delamination durability due to cyclic loading will be presented. The use of this technique for predicting fatigue life of composite laminates and developing a fatigue design philosophy for composite structural components will be reviewed.

  5. High temperature composite materials and magnetodielectric composites for microwave application

    NASA Astrophysics Data System (ADS)

    Do, Thanh Ba

    In the part I, we investigated the microstructures, mechanical properties, and oxidation behavior of hot pressed BN in the presence of sintering additives Al2O3, Y2O3 and SiO2. BN platelets size in the sintered samples grew from ˜5 to ˜30 times for the use of all three oxides, and the use of Al2O3 and Y2O3, correspondingly. The excessive growth of BN platelets in samples containing Al2O3 and Y2O 3 caused them to misalign which, in turn, resulted in its low relative density (92.0%). The use of SiO2 mitigated this grain growth so that BN platelets aligned better to gain a higher relative density (99.5%). Flexural strength and elastic modulus of BN were proportional to their densities. Oxidation experiments conducted at 1200°C in flowing dry air showed borate glass droplets were formed on all of oxidized BN samples. The addition of SiO2 resulted in the formation of a glass layer before the appearance of these glass droplets. The presence of glass droplets was a result of the poor wetting of liquid B2O3 on BN and the dominance of the formation of B2O3 to its evaporation. Their size evolution described the "breadth figure" theory, similar to the formation of water droplets on a flat surface from the saturated water vapor air. Substructures observed inside the glass droplets contained high and consistent Al:Y atomic ratio (5:7) in all samples. The evaporation of B2O 3 isolated Al2O3, Y2O3 in the form of immiscible liquid phase to borate. In the part II, we investigated the formulation of equivalent permittivity and permeability with isotropic and anisotropic Co2Z-polymer composition. These two properties of isotropic Co2Z-LDPE/Co2Z-Silicone composites increased with Co2Z composition. However, their permittivity was always higher than that of their permeability. Permittivity and permeability of anisotropic Co2Z-Silicone composites were split into high and low values along the parallel and perpendicular directions to the alignment direction of Co2Z particles. The separation at 20 vol% Co2Z was strongest, attained 46% anisotropy so that its parallel permeability approached closer to that of its perpendicular permittivity. However, the low permittivity of Co2Z required a higher electric field to increase its particles' alignment.

  6. Composite metal foil and ceramic fabric materials

    DOEpatents

    Webb, Brent J. (Richland, WA); Antoniak, Zen I. (Richland, WA); Prater, John T. (Chapel Hill, NC); DeSteese, John G. (Kennewick, WA)

    1992-01-01

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

  7. The composite materials handbook (MIL handbook 17). Volume 2: Materials properties

    SciTech Connect

    Not Available

    1999-01-01

    The Composite Materials Handbook (MIL Handbook 17) is THE source for data and usage guidelines for current and emerging polymer matrix composite materials. It provides you with the tools you will need to design and fabricate end items from polymer matrix composite materials and offers guidelines for how these data should be generated and used. The Handbook is a comprehensive guide of composites technology and engineering, an area that is advancing and changing rapidly. Data obtained and selected according to Volume 1 are published in Volume 2.

  8. Fast, Contactless Monitoring of the Chemical Composition of Raw Materials

    NASA Astrophysics Data System (ADS)

    Ivanov, O.; Stoyanov, Zh.; Stoyanov, B.; Nadoliisky, M.; Vaseashta, Ashok

    A technique to monitor chemical composition of materials during manufacturing of ceramic products, in particular - of bricks, is investigated. The technique of monitoring is likely to offset environmental pollution and save energy. For this purpose, we use the Surface photo charge effect, which is generated for each solid body interacting with electromagnetic field. The measurement is express and can be performed in-situ in production conditions. The experimental work has shown that different samples of the investigated materials with different compositions produce different signals specific to each sample. For the same material, the signal varies with the change in chemical composition. More specifically, it is shown that for the material from which the bricks are fired, the signal is a function of the percentage of coal sludge. The results indicate that the characterization technique as a viable technique for control of incoming raw materials.

  9. Composite Structures and Materials Research at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, roberto J.

    2003-01-01

    A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

  10. Method of tissue repair using a composite material

    DOEpatents

    Hutchens, Stacy A; Woodward, Jonathan; Evans, Barbara R; O'Neill, Hugh M

    2014-03-18

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  11. Composite Structures and Materials Research at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, Roberto J.

    2001-01-01

    A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI) Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

  12. Bearing material. [composite material with low friction surface for rolling or sliding contact

    NASA Technical Reports Server (NTRS)

    Sliney, H. E. (inventor)

    1976-01-01

    A composite material is described which will provide low friction surfaces for materials in rolling or sliding contact and is self-lubricating and oxidation resistant up to and in excess of about 930 C. The composite is comprised of a metal component which lends strength and elasticity to the structure, a fluoride salt component which provides lubrication and, lastly, a glass component which not only provides oxidation protection to the metal but may also enhance the lubrication qualities of the composite.

  13. Carbon Cryogel Silicon Composite Anode Materials for Lithium Ion Batteries

    NASA Technical Reports Server (NTRS)

    Woodworth James; Baldwin, Richard; Bennett, William

    2010-01-01

    A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 10 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-4,9 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

  14. Composition/bandgap selective dry photochemical etching of semiconductor materials

    DOEpatents

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  15. Composition and process for making an insulating refractory material

    DOEpatents

    Pearson, A.; Swansiger, T.G.

    1998-04-28

    A composition and process are disclosed for making an insulating refractory material. The composition includes calcined alumina powder, flash activated alumina powder, an organic polymeric binder and a liquid vehicle which is preferably water. Starch or modified starch may also be added. A preferred insulating refractory material made with the composition has a density of about 2.4--2.6 g/cm{sup 3} with reduced thermal conductivity, compared with tabular alumina. Of importance, the formulation has good abrasion resistance and crush strength during intermediate processing (commercial sintering) to attain full strength and refractoriness.

  16. Method and apparatus for gripping uniaxial fibrous composite materials

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Hurwitz, F. I. (inventors)

    1984-01-01

    A strip specimen is cut from a unidirectional strong, brittle fiber composite material, and the surfaces of both ends of the specimen are grit blasted. The specimen is then placed between metal load transfer members having grit blasted surfaces. Sufficient compressive stress is applied to the load transfer members to prevent slippage during testing at both elevated temperatures and room temperatures. The need for adhesives, load pads, and other secondary composite processing is eliminated. This gripping system was successful in tensile testing, creep rupture testing, and fatigue testing uniaxial composite materials at 316 C.

  17. Properties of graphite composites based on natural and synthetic graphite powders and a phenolic novolac binder

    NASA Astrophysics Data System (ADS)

    Magampa, P. P.; Manyala, N.; Focke, W. W.

    2013-05-01

    Model graphite composites, similar to those used in nuclear applications as encasement material in fuel pebbles, were prepared by uniaxial cold compression moulding. They contained natural flake graphite, synthetic graphite and 20 wt.% phenolic novolac resin binder. The materials were carbonised at 900 °C in a nitrogen atmosphere and then annealed at 1800 °C in helium atmosphere. The X-ray diffraction studies showed that the graphite in these composites had hexagonal crystal structure after annealing. Raman spectroscopy revealed the presence of the structurally disordered phase derived from the carbonised resin. Optical microscopy revealed a flake-like microstructure for composites containing mainly natural graphite and needle-coke like particles for composites containing mainly synthetic graphite. The composites featured anisotropic property behaviour as the particles were partially aligned in a direction perpendicular to the compression direction. Thermogravimetric analysis studies showed that the annealed graphite composites were stable in air to 650 °C. The linear thermal expansion coefficients measured by thermomechanical analysis (20-600 °C) in the direction of pressing were in the range 5-9 × 10-6 K-1 and in the range 1.2-2 × 10-6 K-1 in the direction normal to pressing. The thermal conductivity of the composites were measured using Xenon flash method from 100 to 1000 °C and the values ranged from 19 to 30 W m-1 K-1.

  18. Advanced Composite Materials and Steel Retrofitting Techniques for Seismic Strengthening of Low-Rise Structures: Review

    Microsoft Academic Search

    Houssam Toutanji; Holley Britton; M. Han

    \\u000a Low-rise structure collapse can be caused by several different factors including natural disasters, fire, blast, and poor\\u000a construction. This study focuses on preventing collapse due to earthquakes and it is concerned with the retrofit of structures\\u000a against future total collapse using innovative materials, such as fiber reinforced polymer (FRP) composites and traditional\\u000a materials such as steel. A review of recent

  19. Light custodians in natural composite Higgs models

    SciTech Connect

    Contino, Roberto [Dipartimento di Fisica, Universita di Roma 'La Sapienza' and INFN, Piazzale Aldo Moro 2, I-00185 Rome (Italy); Rold, Leandro da [Instituto de Fisica, Universidade de Sao Paulo, Rua do Matao Travessa R, 187, 05508-900 SP (Brazil); Pomarol, Alex [IFAE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

    2007-03-01

    We present a class of composite Higgs models arising from a warped extra dimension that can satisfy all the electroweak precision tests in a significant portion of their parameter space. A custodial symmetry plays a crucial role in keeping the largest corrections to the electroweak observables below their experimental limits. In these models the heaviness of the top quark is not only essential to trigger the electroweak symmetry breaking, but it also implies that the lowest top resonance and its custodial partners, the custodians, are significantly lighter than the other resonances. These custodians are the trademark of these scenarios. They are exotic colored fermions of electromagnetic charges 5/3, 2/3, and -1/3, with masses predicted roughly in the range 500-1500 GeV. We discuss their production and detection at the CERN LHC.

  20. Metal oxide composite dosimeter method and material

    DOEpatents

    Miller, Steven D. (Richland, WA)

    1998-01-01

    The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

  1. Fused silica as a composite nanostructured material

    Microsoft Academic Search

    V. K. Miloslavsky; E. D. Makovetsky; L. A. Ageev; K. S. Beloshenko

    2009-01-01

    A method for calculating the refractive index of optical fused silica by applying the model of effective permittivity of composite\\u000a homogeneous media is proposed and realized. The calculation was performed using the tabular data of the refractive index of\\u000a crystalline ? quartz and the ratio of the quartz glass and ? quartz densities. It was suggested that fused silica contains

  2. Combustion synthesis of advanced composite materials

    Microsoft Academic Search

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product

  3. Synthesis of aluminium nitride/boron nitride composite materials

    SciTech Connect

    Xiao, T.D. (Univ. of Connecticut, Storrs, CT (United States). Polymer Science Program and Dept. of Chemistry); Gonsalves, K.E. (Univ. of Connecticut, Storrs, CT (United States). Polymer Science Program and Dept. of Chemistry Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemistry); Strutt, P.R. (Univ. of Connecticut, Storrs, CT (United States). Dept. of Metallurgy)

    1993-04-01

    Aluminum nitride/boron nitride composite was synthesized by using boric acid, urea, and aluminum chloride (or aluminum lactate) as the starting compounds. The starting materials were dissolved in water and mixed homogeneously. Ammonolysis of this aqueous solution resulted in the formation of a precomposite gel, which converted into the aluminum nitride/boron nitride composite on further heat treatment. Characterization of both the precomposite and the composite powders included powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Analysis of the composite revealed that the aluminum nitride phase had a hexagonal structure, and the boron nitride phase a turbostratic structure.

  4. Surface characteristics of resin composite materials after finishing and polishing.

    PubMed

    St Germain, Henry; Samuelson, Bart A

    2015-01-01

    This in vitro study determined the surface roughness (Ra) and absolute gloss (AG) values for 2 resin composites: a microhybrid and a microfill. Eight groups (n = 4) of each resin composite were prepared, along with 4 controls (Mylar strip) for the 2 resin composites. After finishing with a medium polishing disc, the specimens from each resin composite material were subjected to 7 polishing procedures, and Ra measurements and AG values were determined. Two-way ANOVA and Fisher's LSD multiple comparisons revealed significant differences (P ? 0.05). For both materials, the control group produced the lowest Ra values and highest AG values, and the medium polishing disc produced the highest Ra values and lowest AG values. Of the 2 resin composites, the microhybrid had lower mean Ra and higher mean AG than the microfill for the majority of the polishing procedures. Pearson's r correlation coefficient (P ? 0.001) indicated an inverse linear relationship between Ra and AG. PMID:25734283

  5. Bijel - a novel composite material from colloids on liquid-liquid interfaces 

    E-print Network

    Herzig, Eva M

    2008-01-01

    Composite materials generally consist of different components which individually exhibit an entirely different material behaviour than within the composite. Here, two immiscible liquids are stabilised with solid particles ...

  6. Structurally integrated fiber optic damage assessment system for composite materials.

    PubMed

    Measures, R M; Glossop, N D; Lymer, J; Leblanc, M; West, J; Dubois, S; Tsaw, W; Tennyson, R C

    1989-07-01

    Progress toward the development of a fiber optic damage assessment system for composite materials is reported. This system, based on the fracture of embedded optical fibers, has been characterized with respect to the orientation and location of the optical fibers in the composite. Together with a special treatment, these parameters have been tailored to yield a system capable of detecting the threshold of damage for various impacted Kevlar/epoxy panels. The technique has been extended to measure the growth of a damage region which could arise from either impact, manufacturing flaws, or static overloading. The mechanism of optical fiber fracture has also been investigated. In addition, the influence of embedded optical fibers on the tensile and compressive strength of the composite material has been studied. Image enhanced backlighting has been shown to be a powerful and convenient method of assessing internal damage to translucent composite materials. PMID:20555570

  7. Carbon-carbon composites: Emerging materials for hypersonic flight

    NASA Technical Reports Server (NTRS)

    Maahs, Howard G.

    1989-01-01

    An emerging class of high temperature materials called carbon-carbon composites are being developed to help make advanced aerospace flight become a reality. Because of the high temperature strength and low density of carbon-carbon composites, aerospace engineers would like to use these materials in even more advanced applications. One application of considerable interest is as the structure of the aerospace vehicle itself rather than simply as a protective heat shield as on Space Shuttle. But suitable forms of these materials have yet to be developed. If this development can be successfully accomplished, advanced aerospace vehicles such as the National Aero-Space Plane (NASP) and other hypersonic vehicles will be closer to becoming a reality. A brief definition is given of C-C composites. Fabrication problems and oxidation protection concepts are examined. Applications of C-C composites in the Space Shuttle and in advanced hypersonic vehicles as well as other applications are briefly discussed.

  8. Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance

    SciTech Connect

    Ward, R.M.; Vaughey, J.T.

    2006-01-01

    Composite cathode materials in lithium ion batteries have become the subject of a great amount of research recently as cost and safety issues related to LiCoO2 and other layered structures have been discovered. Alternatives to these layered materials include materials with the spinel and olivine structures, but these present different problems, e.g. spinels have low capacities and cycle poorly at elevated temperatures, and olivines exhibit extremely low intrinsic conductivity. Previous work has shown that composite structures containing spinel and layered materials have shown improved electrochemical properties. These types of composite structures have been studied in order to evaluate their performance and safety characteristics necessary for use in lithium ion batteries in portable electronic devices, particularly hybrid-electric vehicles. In this study, we extended that work to layered-olivine and spinel-olivine composites. These materials were synthesized from precursor salts using three methods: direct reaction, ball-milling, and a coreshell synthesis method. X-ray diffraction spectra and electrochemical cycling data show that the core-shell method was the most successful in forming the desired products. The electrochemical performance of the cells containing the composite cathodes varied dramatically, but the low overpotential and reasonable capacities of the spinel-olivine composites make them a promising class for the next generation of lithium ion battery cathodes.

  9. Development of ductile magnesium composite materials using titanium as reinforcement

    Microsoft Academic Search

    S. F. Hassan; M. Gupta

    2002-01-01

    In the present study, elemental and titanium particulate reinforced magnesium materials were synthesized using an innovative disintegrated melt deposition technique followed by hot extrusion. Microstructural characterization of the composite samples showed reasonably uniform distribution of titanium particulates in the matrix material, strong interfacial integrity of magnesium matrix with titanium particulates, and the presence of minimal porosity. Physical property characterization revealed

  10. On Low-Velocity Impact Testing of Composite Materials

    Microsoft Academic Search

    Peter O. Sjoblom; J. Timothy Hartness; Tobey M. Cordell

    1988-01-01

    The importance of understanding the response of structural composites to impact cannot be overstated. This understanding includes both the impact phenomena themselves and the influence of materials properties on the impact response. This paper presents the need for instrumented testing to optimize our understanding of the impact event, especially the response of the impacted material. The conclusion is drawn that

  11. Data analysis techniques for impact tests of composite materials

    Microsoft Academic Search

    A. L. Svenson; M. W. Hargrave; B. S. Ye; L. C. Bank

    1994-01-01

    This paper discusses data analysis techniques for instrumented impact tests conducted on glass fiber composite materials. For this study, a drop weight tower has been instrumented with an accelerometer and computer data acquisition system. From the acceleration data obtained, load, energy, velocity, and displacement are calculated in a spreadsheet environment. The resulting data from multiple tests for each material type

  12. Topological design of structures and composite materials with multiobjectives

    Microsoft Academic Search

    Niek de Kruijf; Shiwei Zhou; Qing Li; Yiu-Wing Mai

    2007-01-01

    This paper studies the influence of heat conduction in both structural and material designs in two dimensions. The former attempts to find the optimal structures with the maximum stiffness and minimum resistance to heat dissipation and the latter to tailor composite materials with effective thermal conductivity and bulk modulus attaining their upper limits like Hashin–Shtrikman and Lurie–Cherkaev bounds. In the

  13. Insertion loss of sound waves through composite acoustic window materials

    Microsoft Academic Search

    Ji-Hye Lee; Byoung-Nam Kim; Ku-Kyun Shin; Suk Wang Yoon

    2010-01-01

    This study evaluated the insertion loss of sound waves through composite acoustic window materials for sonar dome applications, and examined the influence of dome shape on the sonar performance. The insertion loss of sound waves through acoustic window materials was experimentally measured as a function of frequency at normal incidence. The insertion loss was also theoretically estimated with three- and

  14. The role of polymer based composites materials in modern and future aerospace structures

    NASA Astrophysics Data System (ADS)

    Cantoni, Stefania; De Nicola, Felice; Mercurio, Umberto; Quaranta, Vincenzo

    2014-05-01

    The need to reduce the overall weight of aeronautical and space structures, while at the same time preserving or even improving their performances, make the research and development in the field of innovative structures and advanced composite materials a crucial step for the advancement of aerospace technologies. Several fields of innovation have been explored in the last decades but the most promising solutions for the future of aerospace structures will be found in the "intelligent" use of polymer based composite materials both in the design and in their "nature like" use.

  15. Fibre-Optic Impact Damage Detection Of Composite Materials

    NASA Astrophysics Data System (ADS)

    Measures, R. M.; Glossop, N. D. W.; Lymer, J.; Dubois, S.; Tsaw, W.; West, J.; Tennyson, R. C.

    1988-09-01

    The development of a fibre-optic based damage assessment system for composite material structures requires a base of knowledge that to date is not available in the literature. We report on several advances that will contribute towards the development of "structurally imbedded fibre optic damage evaluation" (SIFODE) technology. These include: devising a special surface treatment that allows control of the damage sensitivity of the optical fibres, determining their optimum orientation with respect to the material fibres in the adjacent plies and their depth in regard to an impact surface. The influence of the imbedded optical fibres on the strength and impact resistance of the composite material has also been investigated.

  16. Polymeric compositions incorporating polyethylene glycol as a phase change material

    SciTech Connect

    Salyer, Ival O. (Dayton, OH); Griffen, Charles W. (Mason, OH)

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the composition is useful in making molded and/or coated materials such as flooring, tiles, wall panels and the like; paints containing polyethylene glycols or end-capped polyethylene glycols are also disclosed.

  17. Emissivity Results on High Temperature Coatings for Refractory Composite Materials

    NASA Technical Reports Server (NTRS)

    Ohlhorst, Craig W.; Vaughn, Wallace L.; Daryabeigi, Kamran; Lewis, Ronald K.; Rodriguez, Alvaro C.; Milhoan, James D.; Koenig, John R.

    2007-01-01

    The directional emissivity of various refractory composite materials considered for application for reentry and hypersonic vehicles was investigated. The directional emissivity was measured at elevated temperatures of up to 3400 F using a directional spectral radiometric technique during arc-jet test runs. A laboratory-based relative total radiance method was also used to measure total normal emissivity of some of the refractory composite materials. The data from the two techniques are compared. The paper will also compare the historical database of Reinforced Carbon-Carbon emissivity measurements with emissivity values generated recently on the material using the two techniques described in the paper.

  18. Workshop on Scaling Effects in Composite Materials and Structures

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E. (compiler)

    1994-01-01

    This document contains presentations and abstracts from the Workshop on Scaling Effects in Composite Materials and Structures jointly sponsored by NASA Langley Research Center, Virginia Tech, and the Institute for Mechanics and Materials at the University of California, San Diego, and held at NASA Langley on November 15-16, 1993. Workshop attendees represented NASA, other government research labs, the aircraft/rotorcraft industry, and academia. The workshop objectives were to assess the state-of-technology in scaling effects in composite materials and to provide guidelines for future research.

  19. The damage, repair and design of fiber composite structural materials

    SciTech Connect

    Chu, Fa-De Jack.

    1992-01-01

    Three aspects of the repair of fiber reinforced composite materials were examined in this study. First, the in-plane compression damage of four typical fiber composite materials was studied, and different repair strategies were explored. Second, an optimum composite sheet design for least damaged by buckling and easiest to repair was studied. Third, anhydride-cured epoxy adhesive and E-glass fibers/vinyl ester matrix, which is critical to the quality of the repair, was investigated. For none of the four typical fiber composite materials subjected to in-plane compression do all of the load carrying fibers break, and those do are usually in easily removal layers. Moreover, the behavior of each material was relatively consistent. As a result, a new repair strategy is proposed in which nor more of the load-carrying fibers are removed from the damage zone than are broken. For the two laminated materials, a transition in failure mode form tensile to shear was found as the effective gage length of the specimen decreased. This suggests that the composite structure can be designed to relieve the applied can be designed to relieve the applied load in desired locations and with benign failure modes. In the second part, ten composite materials with different fiber stacking sequences were subjected to in-plane compression. Three failure modes were dominant: shear, delamination buckling, and flexural failure. The volume of damage occurring in the 0[degrees]-fiber plies decreased lamination buckling failure. With respect to the amount of damage and repair strength recovery, it is best to have the composite structure designed to fail in delamination buckling when failure is inevitable. In the third part, model system were used to simulate the interfacial region between adhesive and adherent. These involved curing the adhesive against FTIR-ATR plate and against adherent material ground to a fine powder to greatly increase its surface area.

  20. Composite materials based on wastes of flat glass processing.

    PubMed

    Gorokhovsky, A V; Escalante-Garcia, J I; Gashnikova, G Yu; Nikulina, L P; Artemenko, S E

    2005-01-01

    Glass mirrors scrap and poly (vinyl) butiral waste (PVB) obtained from flat glass processing plants were investigated as raw materials to produce composites. The emphasis was on studying the influence of milled glass mirror waste contents on properties of composites produced with PVB. The characterization involved: elongation under rupture, water absorption, tensile strength and elastic modulus tests. The results showed that the composite containing 10 wt% of filler powder had the best properties among the compositions studied. The influence of the time of exposure in humid atmosphere on the composite properties was investigated. It was found that the admixture of PVB iso-propanol solution to the scrap of glass mirrors during milling provided stabilization of the properties of the composites produced. PMID:16009308

  1. Composite Materials with Viscoelastic Stiffness Greater Than Diamond

    NASA Astrophysics Data System (ADS)

    Jaglinski, T.; Kochmann, D.; Stone, D.; Lakes, R. S.

    2007-02-01

    We show that composite materials can exhibit a viscoelastic modulus (Young's modulus) that is far greater than that of either constituent. The modulus, but not the strength, of the composite was observed to be substantially greater than that of diamond. These composites contain barium-titanate inclusions, which undergo a volume-change phase transformation if they are not constrained. In the composite, the inclusions are partially constrained by the surrounding metal matrix. The constraint stabilizes the negative bulk modulus (inverse compressibility) of the inclusions. This negative modulus arises from stored elastic energy in the inclusions, in contrast to periodic composite metamaterials that exhibit negative refraction by inertial resonant effects. Conventional composites with positive-stiffness constituents have aggregate properties bounded by a weighted average of constituent properties; their modulus cannot exceed that of the stiffest constituent.

  2. Composite materials with viscoelastic stiffness greater than diamond.

    PubMed

    Jaglinski, T; Kochmann, D; Stone, D; Lakes, R S

    2007-02-01

    We show that composite materials can exhibit a viscoelastic modulus (Young's modulus) that is far greater than that of either constituent. The modulus, but not the strength, of the composite was observed to be substantially greater than that of diamond. These composites contain bariumtitanate inclusions, which undergo a volume-change phase transformation if they are not constrained. In the composite, the inclusions are partially constrained by the surrounding metal matrix. The constraint stabilizes the negative bulk modulus (inverse compressibility) of the inclusions. This negative modulus arises from stored elastic energy in the inclusions, in contrast to periodic composite metamaterials that exhibit negative refraction by inertial resonant effects. Conventional composites with positive-stiffness constituents have aggregate properties bounded by a weighted average of constituent properties; their modulus cannot exceed that of the stiffest constituent. PMID:17272714

  3. Probing disease-related proteins with fluorogenic composite materials.

    PubMed

    He, Xiao-Peng; Zang, Yi; James, Tony D; Li, Jia; Chen, Guo-Rong

    2015-07-01

    Construction of composite materials based on the self-assembly of fluorescently labeled biomolecules with a variety of micro- or nano-quenching materials (by the Förster Resonance Energy Transfer mechanism) for the fluorogenic recognition of disease-related proteins has become a dynamic research topic in the field of fluorescence recognition. Here we summarize the recent progress on the composition of fluorescence dye-labeled biomolecules including sugars, peptides and nucleotides with organic (graphene and carbon nanotubes) and inorganic (gold nanoparticles) materials. Their application in the fluorescence detection of proteins and enzymes on both the molecular and cellular levels is discussed. Perspectives are proposed with respect to the future directions of employing these composite materials in the recognition of pathological proteins. PMID:25474366

  4. Light weight polymer matrix composite material

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J. (inventor); Lowell, Carl E. (inventor)

    1988-01-01

    A graphite fiber reinforced polymer matrix is layed up, cured, and thermally aged at about 750 F in the presence of an inert gas. The heat treatment improves the structural integrity and alters the electrical conductivity of the materials. In the preferred embodiment PMR-15 polyimides and Celion-6000 graphite fibers are used.

  5. A grammatical approach to customization of shape and composite materials

    NASA Astrophysics Data System (ADS)

    Nandi, Soumitra

    With the increasing use of composite materials in Mechanical and Aerospace industries, an approach is required to facilitate designing of components using composite materials, while ensuring customization of the shape such a way that multiple design goals for the components are satisfied. Existing design methods may be used in some cases, where the component shape and loadings are simple. While a significant amount of research has been conducted to study the properties of composite materials, little attention has been paid to find out a design approach such that (1) the user requirements in the very general form may be used directly and as the input for the design, (2) the best possible composite material are selected to meet multiple desired functions, and (3) shape variation is analyzed in order to enable mass customization of the design. Thus an approach is required that will be able to handle both the shape and the material in order to design a load bearing component using composite materials. In this research the focus is to develop a design approach that will consider the user requirements for a composite component in its very general form and generate component shape and material details in a systematic order so that the designed component can withstand a given loading condition. Consequently, the Primary Research Question is: How to simultaneously explore shape and composite materials during the design of a product to meet multiple property and functional goals? The wide range of properties, covered by various fiber-matrix combinations, along with their directional property characteristics, maximizes the flexibility of the designers, while designing composite material products. Meeting multiple property goals, however, complicates the design process as both the composite material selection and the component shape formation becomes highly intricate with the loading conditions and a number of matrix calculations needs to be performed to determine theoretical value of composite material properties. A grammar is a formal definition of a language written in transformational form. To address these issues, in this research a grammatical approach is developed that will generate a shape grammar to perform shape optimization, and then incorporate a composite material selection system and loading analysis techniques of Solid Mechanics in order to design load bearing components of irregular shape. The approach will be able to consider the user requirements in the very general text form, convert them to the design requirements for the component, generate optimized shape based on multiple design constraints, perform the complete design work, and generate the component. The major contributions include: (1) generating a shape grammar to represent functions of the load bearing component such a way that mass-customization of shape is possible, (2) developing a composite material customization system in order to satisfy directional property requirements, and (3) introducing a unique laminate design approach in order to satisfy design property requirements at the critical cross-sections locally that can result in highly efficient design compared to conventional design method. Verification of the approach will focus on its application to simultaneously explore shapes and customization of composite materials.

  6. Material Damping Analysis of a Smart Hybrid Composite Lamina

    Microsoft Academic Search

    Vijayan Baburaj; Yuji Matsuzaki

    1994-01-01

    This paper addresses an analytical approach to evaluate the inherent material Specific Damping Capacity (SDC) of a smart hybrid fiber reinforced polymer composite lamina. Analytical equations for the material specific damping capacity have been derived by assuming a linear viscoelastic material property for the constituent fiber-matrix system. The damping properties corresponding to all the six in-plane and out-of-plane applied stresses

  7. Ultrasonic Monitoring of Material Degradation in FRP Composites

    Microsoft Academic Search

    Olajide D. Dokun; Laurence J. Jacobs; Rami M. Haj-Ali

    2000-01-01

    This research uses laser ultrasonic techniques to monitor a (directly measurable) ultrasonic prop- erty—frequency-dependent Rayleigh wave velocity (material dispersion)—and then relates changes in this acoustic property to changes in the material's properties (such as stiffness) that characterize damage. The subject material system is a thick, glass-reinforced, vinylester (thermosetting) fiber-reinforced polymer (FRP) composite. Laser ultrasonics is an ideal methodology to monitor

  8. Composite materials research and education program: The NASA-Virginia Tech composites program

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1980-01-01

    Major areas of study include: (1) edge effects in finite width laminated composites subjected to mechanical, thermal and hygroscopic loading with temperature dependent material properties and the influence of edge effects on the initiation of failure; (2) shear and compression testing of composite materials at room and elevated temperatures; (3) optical techniques for precise measurement of coefficients of thermal expansion of composites; (4) models for the nonlinear behavior of composites including material nonlinearity and damage accumulation and verification of the models under biaxial loading; (5) compressive failure of graphite/epoxy plates with circular holes and the buckling of composite cylinders under combined compression and torsion; (6) nonlinear mechanical properties of borsic/aluminum, graphite/polyimide and boron/aluminum; (7) the strength characteristics of spliced sandwich panels; and (8) curved graphite/epoxy panels subjected to internal pressure.

  9. Review on advanced composite materials boring mechanism and tools

    NASA Astrophysics Data System (ADS)

    Shi, Runping; Wang, Chengyong

    2011-05-01

    With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher specific strength and higher specific modulus than glass fibre reinforced resin composites of the 1st generation. They are widely used in aviation and aerospace industry due to their high specific strength, high specific modulus, excellent ductility, anticorrosion, heat-insulation, sound-insulation, shock absorption and high&low temperature resistance. They are used for radomes, inlets, airfoils(fuel tank included), flap, aileron, vertical tail, horizontal tail, air brake, skin, baseboards and tails, etc. Its hardness is up to 62~65HRC. The holes are greatly affected by the fibre laminates direction of carbon fibre reinforced composite material due to its anisotropy when drilling in unidirectional laminates. There are burrs, splits at the exit because of stress concentration. Besides there is delamination and the hole is prone to be smaller. Burrs are caused by poor sharpness of cutting edge, delamination, tearing, splitting are caused by the great stress caused by high thrust force. Poorer sharpness of cutting edge leads to lower cutting performance and higher drilling force at the same time. The present research focuses on the interrelation between rotation speed, feed, drill's geometry, drill life, cutting mode, tools material etc. and thrust force. At the same time, holes quantity and holes making difficulty of composites have also increased. It requires high performance drills which won't bring out defects and have long tool life. It has become a trend to develop super hard material tools and tools with special geometry for drilling composite materials.

  10. Review on advanced composite materials boring mechanism and tools

    NASA Astrophysics Data System (ADS)

    Shi, Runping; Wang, Chengyong

    2010-12-01

    With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher specific strength and higher specific modulus than glass fibre reinforced resin composites of the 1st generation. They are widely used in aviation and aerospace industry due to their high specific strength, high specific modulus, excellent ductility, anticorrosion, heat-insulation, sound-insulation, shock absorption and high&low temperature resistance. They are used for radomes, inlets, airfoils(fuel tank included), flap, aileron, vertical tail, horizontal tail, air brake, skin, baseboards and tails, etc. Its hardness is up to 62~65HRC. The holes are greatly affected by the fibre laminates direction of carbon fibre reinforced composite material due to its anisotropy when drilling in unidirectional laminates. There are burrs, splits at the exit because of stress concentration. Besides there is delamination and the hole is prone to be smaller. Burrs are caused by poor sharpness of cutting edge, delamination, tearing, splitting are caused by the great stress caused by high thrust force. Poorer sharpness of cutting edge leads to lower cutting performance and higher drilling force at the same time. The present research focuses on the interrelation between rotation speed, feed, drill's geometry, drill life, cutting mode, tools material etc. and thrust force. At the same time, holes quantity and holes making difficulty of composites have also increased. It requires high performance drills which won't bring out defects and have long tool life. It has become a trend to develop super hard material tools and tools with special geometry for drilling composite materials.

  11. Development of chemical vapor composites, CVC materials. Final report

    SciTech Connect

    NONE

    1998-10-05

    Industry has a critical need for high-temperature operable ceramic composites that are strong, non-brittle, light weight, and corrosion resistant. Improvements in energy efficiency, reduced emissions and increased productivity can be achieved in many industrial processes with ceramic composites if the reaction temperature and pressure are increased. Ceramic composites offer the potential to meet these material requirements in a variety of industrial applications. However, their use is often restricted by high cost. The Chemical Vapor composite, CVC, process can reduce the high costs and multiple fabrication steps presently required for ceramic fabrication. CVC deposition has the potential to eliminate many difficult processing problems and greatly increase fabrication rates for composites. With CVC, the manufacturing process can control the composites` density, microstructure and composition during growth. The CVC process: can grow or deposit material 100 times faster than conventional techniques; does not require an expensive woven preform to infiltrate; can use high modulus fibers that cannot be woven into a preform; can deposit composites to tolerances of less than 0.025 mm on one surface without further machining.

  12. Acoustic emission from composite materials. [nondestructive tests

    NASA Technical Reports Server (NTRS)

    Visconti, I. C.; Teti, R.

    1979-01-01

    The two basic areas where the acoustic emission (AE) technique can be applied are materials research and the evaluation of structural reliability. This experimental method leads to a better understanding of fracture mechanisms and is an NDT technique particularly well suited for the study of propagating cracks. Experiments are described in which acoustic emissions were unambiguously correlated with microstructural fracture mechanisms. The advantages and limitations of the AE technique are noted.

  13. Accelerated hygrothermal stabilization of composite materials

    SciTech Connect

    Gale, J.A.

    1994-05-01

    Experimentation validated a simple moisture conditioning scheme to prepare Gr/Ep composite parts for precision applications by measuring dimensional changes over 90 days. It was shown that an elevated temperature moisture conditioning scheme produced a dimensionally stable part from which precision structures could be built/machined without significant moisture induced dimensional changes after fabrication. Conversely, that unconditioned Gr/Ep composite panels exhibited unacceptably large dimensional changes (i.e., greater than 125 ppM). It was also shown that time required to produce stable parts was shorter, by more than an order of magnitude, employing the conditioning scheme than using no conditioning scheme (46 days versus 1000+ days). Two final use environments were chosen for the experiments: 50% RH/21C and 0% RH/21C. Fiberite 3034K was chosen for its widespread use in aerospace applications. Two typical lay-ups were chosen, one with low sensitivity to hygrothermal distortions and the other high sensitivity: [0, {plus_minus} 45, 90]s, [0, {plus_minus} 15, 0]s. By employing an elevated temperature, constant humidity conditioning scheme, test panels achieved an equilibrium moisture content in less time, by more than an order of magnitude, than panels exposed to the same humidity environment and ambient temperature. Dimensional changes, over 90 days, were up to 4 times lower in the conditioned panels compared to unconditioned panels. Analysis of weight change versus time of test coupons concluded that the out-of-autoclave moisture content of Fiberite 3034K varied between 0.06 and 0.1%.

  14. Fabrication of a nanostructured gold-polymer composite material

    NASA Astrophysics Data System (ADS)

    Mallick, K.; Witcomb, M.; Scurrell, M.

    2006-07-01

    A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent for both the AP and the water solution of HAuCl4. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the reduction of AuCl4- results in the formation of gold nanoparticles (˜ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the composite material.

  15. Probabilistic fatigue life prediction of metallic and composite materials

    NASA Astrophysics Data System (ADS)

    Xiang, Yibing

    Fatigue is one of the most common failure modes for engineering structures, such as aircrafts, rotorcrafts and aviation transports. Both metallic materials and composite materials are widely used and affected by fatigue damage. Huge uncertainties arise from material properties, measurement noise, imperfect models, future anticipated loads and environmental conditions. These uncertainties are critical issues for accurate remaining useful life (RUL) prediction for engineering structures in service. Probabilistic fatigue prognosis considering various uncertainties is of great importance for structural safety. The objective of this study is to develop probabilistic fatigue life prediction models for metallic materials and composite materials. A fatigue model based on crack growth analysis and equivalent initial flaw size concept is proposed for metallic materials. Following this, the developed model is extended to include structural geometry effects (notch effect), environmental effects (corroded specimens) and manufacturing effects (shot peening effects). Due to the inhomogeneity and anisotropy, the fatigue model suitable for metallic materials cannot be directly applied to composite materials. A composite fatigue model life prediction is proposed based on a mixed-mode delamination growth model and a stiffness degradation law. After the development of deterministic fatigue models of metallic and composite materials, a general probabilistic life prediction methodology is developed. The proposed methodology combines an efficient Inverse First-Order Reliability Method (IFORM) for the uncertainty propogation in fatigue life prediction. An equivalent stresstransformation has been developed to enhance the computational efficiency under realistic random amplitude loading. A systematical reliability-based maintenance optimization framework is proposed for fatigue risk management and mitigation of engineering structures.

  16. 782 NATURE MATERIALS | VOL 12 | SEPTEMBER 2013 | www.nature.com/naturematerials news & views

    E-print Network

    Homes, Christopher C.

    . Another promising avenue, reported by Hu and co-workers2 in Nature Materials, is to make colossal for several different processes in Fig. 1). There are several promising candidate systems for achieving782 NATURE MATERIALS | VOL 12 | SEPTEMBER 2013 | www.nature.com/naturematerials news & views T he

  17. Modeling the thermal properties and processing of composite materials

    SciTech Connect

    Pitchumani, R.

    1992-01-01

    The manufacture of partially cured, thermoset matrix composite systems is modeled. A generalized analysis, applicable to almost all the fiber-resin systems encountered in practice, is carried out in terms of four key dimensionless groups formed of the process and the product parameters - (1) the Damkohler number (K(sub o)) which is a relative measure of the conduction and the reaction time scales, (2) the dimensionless activation energy (E(sub o)), (3) the adiabatic reaction temperature (B(sub o)) which represents the temperature rise potential in the composite due to the heat of the cure reaction, and (4) the Biot number (B(sub i)) which characterizes the post-cure convective cooling of the composite product. Optimal cure cycles which yield a homogeneous cure in the composite, are obtained as a function of the dimensionless parameters. Design plots for the optimal cure temperature and duration are presented. Their use in practical situations is illustrated in the context of a commercially available graphite-epoxy prepreg from Hercules, which is widely used in the aerospace industry. The thermal properties of the composite namely, the transient thermal diffusivity and the steady state thermal conductivity, are essential parameters in the process modeling studies, as well for the design of composite materials for several high temperature applications. Transient heat conduction in fibrous composites is investigated with the aim of devising a criterion for the validity of the analysis of composite materials as homogeneous media having the effective thermal properties. A homogeneity criterion based on the composite thickness is derived in terms of the fiber volume fraction and the fiber diameter. The criterion, which is the first of its kind for fibrous composites, is valid in the practical range of composite parameters. An analytical means for evaluating the effective thermal diffusivity is also presented.

  18. Natural fibres as reinforcement in polylactic acid (PLA) composites

    Microsoft Academic Search

    K. Oksman; M. Skrifvars; J.-F. Selin

    2003-01-01

    The focus in this work has been to study if natural fibres can be used as reinforcement in polymers based on renewable raw materials. The materials have been flax fibres and polylactic acid (PLA). PLA is a thermoplastic polymer made from lactic acid and has mainly been used for biodegradable products, such as plastic bags and planting cups, but in

  19. Multi-objective shape and material optimization of composite structures including damping

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Chamis, Christos C.

    1990-01-01

    A multi-objective optimal design methodology is developed for light-weight, low cost composite structures of improved dynamic performance. The design objectives include minimization of resonance amplitudes (or maximization of modal damping), weight, and material cost. The design vector includes micromechanics, laminate, and structural shape parameters. Performance constraints are imposed on static displacements, dynamic amplitudes, and natural frequencies. The effects of damping on the dynamics of composite structures are incorporated. Preliminary applications on a cantilever composite beam illustrated that only the proposed multi-objective optimization, as opposed to single objective functions, simultaneously improved all objectives. The significance of composite damping in the design of advanced composite structures was also demonstrated, indicating the design methods based on undamped dynamics may fail to improve the dynamic performance near resonances.

  20. On the Natural Hierarchical Composition of Cliques in Cell Assemblies

    E-print Network

    Wennekers, Thomas

    On the Natural Hierarchical Composition of Cliques in Cell Assemblies Thomas Wennekers Ó Springer'' assemblies can form by synaptic T. Wennekers (&) Centre for Theoretical and Computational Neuroscience, Devon, UK e-mail: Thomas.Wennekers@plymouth.ac.uk 123 Cogn Comput DOI 10.1007/s12559-008-9004-5 #12

  1. Thermal degradation of epoxy\\/natural zeolite composites

    Microsoft Academic Search

    Jae-Young Lee; Mi-Ja Shim; Sang-Wook Kim

    2001-01-01

    The characteristics of thermal degradation of epoxy system filled with natural zeolite were studied by thermogravimetry analysis (TGA). All the epoxy composites were degraded in one stage regardless of the zeolite content. In the Freeman & Carroll equation, the activation energy at 20 phr of zeolite was lower than that at any other content of zeolite and these values decreased

  2. A new ferromagnetic hysteresis model for soft magnetic composite materials

    NASA Astrophysics Data System (ADS)

    Zidari?, Bogomir; Miljavec, Damijan

    2011-01-01

    A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.

  3. Life Modeling and Design Analysis for Ceramic Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The primary research efforts focused on characterizing and modeling static failure, environmental durability, and creep-rupture behavior of two classes of ceramic matrix composites (CMC), silicon carbide fibers in a silicon carbide matrix (SiC/SiC) and carbon fibers in a silicon carbide matrix (C/SiC). An engineering life prediction model (Probabilistic Residual Strength model) has been developed specifically for CMCs. The model uses residual strength as the damage metric for evaluating remaining life and is posed probabilistically in order to account for the stochastic nature of the material s response. In support of the modeling effort, extensive testing of C/SiC in partial pressures of oxygen has been performed. This includes creep testing, tensile testing, half life and residual tensile strength testing. C/SiC is proposed for airframe and propulsion applications in advanced reusable launch vehicles. Figures 1 and 2 illustrate the models predictive capabilities as well as the manner in which experimental tests are being selected in such a manner as to ensure sufficient data is available to aid in model validation.

  4. Grained composite materials prepared by combustion synthesis under mechanical pressure

    DOEpatents

    Dunmead, Stephen D. (Davis, CA); Holt, Joseph B. (San Jose, CA); Kingman, Donald D. (Danville, CA); Munir, Zuhair A. (Davis, CA)

    1990-01-01

    Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

  5. Global/local finite element analysis of composite materials

    NASA Technical Reports Server (NTRS)

    Griffin, O. Hayden, Jr.; Vidussoni, M. A.

    1988-01-01

    The motivation for performing global/local finite element analysis in composite materials is described. An example of such an analysis of a composite plate with a central circular hole is presented. Deformed finite element grids and interlaminar normal stress distributions are presented to aid understanding of the plate response. Such distribution at the plate edge is shown to be basically unaffected, although transverse displacements of the edge were slightly different from an analysis of a similar plate with no hole.

  6. Experimental Investigation of Textile Composite Materials Using Moire Interferometry

    NASA Technical Reports Server (NTRS)

    Ifju, Peter G.

    1995-01-01

    The viability as an efficient aircraft material of advanced textile composites is currently being addressed in the NASA Advanced Composites Technology (ACT) Program. One of the expected milestones of the program is to develop standard test methods for these complex material systems. Current test methods for laminated composites may not be optimum for textile composites, since the architecture of the textile induces nonuniform deformation characteristics on the scale of the smallest repeating unit of the architecture. The smallest repeating unit, also called the unit cell, is often larger than the strain gages used for testing of tape composites. As a result, extending laminated composite test practices to textiles can often lead to pronounced scatter in material property measurements. It has been speculated that the fiber architectures produce significant surface strain nonuniformities, however, the magnitudes were not well understood. Moire interferometry, characterized by full-field information, high displacement sensitivity, and high spatial resolution, is well suited to document the surface strain on textile composites. Studies at the NASA Langley Research Center on a variety of textile architectures including 2-D braids and 3-D weaves, has evidenced the merits of using moire interferometry to guide in test method development for textile composites. Moire was used to support tensile testing by validating instrumentation practices and documenting damage mechanisms. It was used to validate shear test methods by mapping the full-field deformation of shear specimens. Moire was used to validate open hole tension experiments to determine the strain concentration and compare then to numeric predictions. It was used for through-the-thickness tensile strength test method development, to verify capabilities for testing of both 2-D and 3-D material systems. For all of these examples, moire interferometry provided vision so that test methods could be developed with less speculation and more documentation.

  7. Properties of laminated steel-silver composite materials

    Microsoft Academic Search

    V. P. Maiboroda

    1974-01-01

    1.The tensile strength sv (130 kg mm2) and microhardness HV (350 kg\\/mm2) of 08kp steel-Ag multilayer composite materials (MCM) substantially exceed both sv and HV of alloy mixtures of the same composition (65 and 150 kg\\/mm2, respectively) and sv and HV of 08kp steel (90 and 180–200 kg\\/mm2, respectively).2.The gain in strength ?sv due to the work-hardening induced by rolling

  8. Progress in very lightweight optics using graphite fiber composite materials

    Microsoft Academic Search

    Peter C. Chen; Timo T. Saha; Andrew M. Smith; Robert C. Romeo

    1998-01-01

    We report progress in the fabrication of very low areal density (< 5 kg\\/m2) optical mirrors using space-flight-qualified graphite-fiber-reinforced cyanate ester composite materials. Previous attempts have been thwarted by fiber print-through at the surface. We find that the problem can be successfully overcome if the composite is processed to leave a very thin layer of resin at the surface. Results

  9. Biotransformation of an uncured composite material

    NASA Technical Reports Server (NTRS)

    Welsh, Clement J.; Glass, Michael J.; Cheslack, Brian; Pryor, Robert; Tran, Duan K.; Bowers-Irons, Gail

    1994-01-01

    The feasibility of biologically degrading prepreg wastes was studied. The work was conducted with the intention of obtaining baseline data that would facilitate the achievement of two long-range goals. These goals are: (1) the biological remediation of the hazardous components in the prepreg wastes, and (2) providing the potential for recycling the prepreg waste fibers. The experiments examined a prepreg that employs an bismaleimide resin system. Initial results demonstrated an obvious deterioration of the prepreg material when incubated with several bacterial strains. The most active cultures were identified as a mixture of 'Bacillus cereus' and 'Pseudomonas sp'. Gas chromatography analyses revealed seven primary compounds in the resin mixture. Biotransformation studies, using the complete prepreg material, demonstrated on obvious loss of all seven organic compounds. Gas chromatography-mass spectrometry analyses resulted in structure assignments for the two primary components of the resin. Both were analogs of Bisphenol A; one being bismaleimide, and the other being Bisphenol A containing a diglycidyl moiety. The 'diglycidyl analog' was purified using thin-layer chromatography and the biotransformation of this compound (at 27 ug/ml bacterial culture) was monitored. After a seven-day incubation, approximately 40% of the organic compound was biotransformed. These results demonstrate the biotransformation of the prepreg resin and indicate that biological remediation of the prepreg wastes is feasible.

  10. Thermal radiation transmission through composite material

    NASA Astrophysics Data System (ADS)

    Loucks, Richard B.

    1995-06-01

    On 10 June 1993, the Defense Nuclear Agency (DNA) Field Command at White Sands Missile Range conducted a Thermal Radiation Simulator (TRS) test for the Naval Surface Warfare Center (NSWC) during project MINOR UNCLE. The NSWC was interested in measuring the radiant thermal energy absorbed by a fiberglass panel during a simulated nuclear weapon event. The resultant thermocouple data showed an unusual initial high-temperature rise and fall, followed by the expected conductive heating. The initial transient was theorized to be the result of thermal radiation transmitted through the panel. To investigate this theory, NSWC prepared several more panels of different thicknesses, preinstrumented with thermocouples and strain gages for testing with a U.S. Army Research Laboratory (ARL) TRS. ARL also provided additional instrumentation to measure thermal radiation on the front surface as well as behind the panel. The results showed that there was direct heating of the rear of the composite panel by thermal radiation. The quantity of heat transmission through the panel and the point of ignition of the front surface of the panel were determined. Smoke and charring of the front surface protected the panel from further heating and possible destruction.

  11. Composite material fabrication techniques. CRADA final report

    SciTech Connect

    Frame, B J; Paulauskas, F L [Oak Ridge National Lab., TN (United States); Miller, J; Parzych, W [Metters Industries, Inc. (United States)

    1996-09-30

    This report describes a low cost method of fabricating components for mockups and training simulators used in the transportation industry. This technology was developed jointly by the Oak Ridge National Laboratory (ORNL) and Metters Industries, Incorporated (MI) as part of a Cooperative Research and Development Agreement (CRADA) ORNL94-0288 sponsored by the Department of Energy (DOE) Office of Economic Impace and Diversity Minority Business Technology Transfer Consortium. The technology involves fabricating component replicas from fiberglass/epoxy composites using a resin transfer molding (RTM) process. The original components are used as masters to fabricate the molds. The molding process yields parts that duplicate the significant dimensional requirements of the original component while still parts that duplicate the significant dimensional requirements of the original component while still providing adequate strength and stiffness for use in training simulators. This technology permits MI to overcome an acute shortage in surplus military hardware available to them for use in manufacturing training simulators. In addition, the cost of the molded fiberglass components is expected to be less than that of procuring the original components from the military.

  12. Pin bearing evaluation of LTM25 composite materials

    NASA Technical Reports Server (NTRS)

    Shah, C. H.; Postyn, A. S.

    1996-01-01

    This report summarizes pin bearing evaluations of LTM25 composite materials. Northrop Grumman Corporation conducted pin bearing testing and fabricate two panels from composite materials that cure at low temperatures. These materials are being incorporated into Unmanned Aerial Vehicles (UAVS) to reduce manufacturing costs since they allow the use of low-cost tooling and facilities. Two composite prepreg product forms were evaluated; MR50/LTM25 unidirectional tape, batch 2881vd and CFS003/LTM25 woven cloth, batch 2216. Northrop Grumman fabricated, machined, and tested specimens to determine the bearing strength in accordance with MIL-HDBK-17D, Volume 1, Section 7.2.4. Quasi-isotropic laminates from the two product forms were fabricated for these tests. In addition, 2 quasi-isotropic panels of dimensions 12 in. x 28 in. were fabricated (one each from the two product forms), inspected, and shipped to NASA Langley for further evaluation.

  13. Composite materials applied to the E-ELT structure

    NASA Astrophysics Data System (ADS)

    Pajuelo, Eugenio; Gómez, José Ramón; Ronquillo, Bernardo; Brunetto, Enzo; Koch, Fran

    2008-07-01

    The upper part of the European Extremely Large Telescope (E-ELT) altitude structure is one of the most critical areas of the telescope's structure. This part hosts sensitive optical elements of the telescope. Its structural performance has a major impact on the whole system. The most critical requirements are low optical path obscuration, high static and dynamic performance (high specific modulus), high mechanical safety (high specific strength), low wind cross section and low weight. Composite materials are ideally suited to meet these requirements. This study is carried out in order to quantify the relative advantage of composite material over mild steel, in terms of performance and costs. The mechanical behavior of the steel structure can be easily improved with a structure manufactured with composite materials. This structure is significantly lighter than the steel one and reduces relative displacements between primary and secondary mirror. Consequently, optical performance is improved, assembly process is simplified and transport cost is reduced.

  14. Effects of thermal cycling on composite materials for space structures

    NASA Technical Reports Server (NTRS)

    Tompkins, Stephen S.

    1989-01-01

    The effects of thermal cycling on the thermal and mechanical properties of composite materials that are candidates for space structures are briefly described. The results from a thermal analysis of the orbiting Space Station Freedom is used to define a typical thermal environment and the parameters that cause changes in the thermal history. The interactions of this environment with composite materials are shown and described. The effects of this interaction on the integrity as well as the properties of GR/thermoset, Gr/thermoplastic, Gr/metal and Gr/glass composite materials are discussed. Emphasis is placed on the effects of the interaction that are critical to precision spacecraft. Finally, ground test methodology are briefly discussed.

  15. Investigation of the anisotropic nature of laser-generated ultrasound in zinc and unidirectional carbon epoxy composites

    Microsoft Academic Search

    David H. Hurley; James B. Spicer; James W. Wagner; Todd W. Murray

    1998-01-01

    Laser generation of ultrasound in carbon epoxy composites provides an ultrasonic signature which is difficult to interpret owing to the elastic anisotropic and inhomogeneous nature of these materials. In the present work, a line source representation of laser-generated ultrasound in materials exhibiting transverse isotropy is presented. The bounding plane of the half-space is assumed to be the plane of isotropy.

  16. Brazing of sheet composite materials with aluminium matrix

    NASA Astrophysics Data System (ADS)

    Khorunov, V. F.; Kuchuk-Iatsenko, V. S.; Dykhno, I. S.; Kasatkina, N. V.

    The technique of brazing composite sheets with an aluminum matrix is investigated for Al matrices with either stainless steel or boron fibers. Brazing is compared to other joining techniques, and the relationship between heating and pressure levels is studied by characterizing the joint qualities microscopically. Solder composition is similarly analyzed, and brazing recommendations are given for ranges of joint sizes. Calculations of the temperature fields for the brazing of these composite materials yield specific-heat input data. Optimal brazing modes thus derived for the Al-matrix composites yield joints free of the intermetallide phases that degrade the performance of brazed structures. The tensile strength of the optimized joints is shown to be good relative to the strength of the original composites with Al matrices.

  17. On the Mechanical Behavior of Advanced Composite Material Structures

    NASA Astrophysics Data System (ADS)

    Vinson, Jack

    During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

  18. Hot extruded carbon nanotube reinforced aluminum matrix composite materials

    NASA Astrophysics Data System (ADS)

    Kwon, Hansang; Leparoux, Marc

    2012-10-01

    Carbon nanotube (CNT) reinforced aluminum (Al) matrix composite materials were successfully fabricated by mechanical ball milling followed by powder hot extrusion processes. Microstructural analysis revealed that the CNTs were well dispersed at the boundaries and were aligned with the extrusion direction in the composites obtained. Although only a small quantity of CNTs were added to the composite (1 vol%), the Vickers hardness and the tensile strength were significantly enhanced, with an up to three-fold increase relative to that of pure Al. From the fractography of the extruded Al-CNT composite, several shapes were observed in the fracture surface, and this unique morphology is discussed based on the strengthening mechanism. The damage in the CNTs was investigated with Raman spectroscopy. However, the Al-CNT composite materials were not only strengthened by the addition of CNTs but also enhanced by several synergistic effects. The nanoindentation stress-strain curve was successfully constructed by setting the effective zero-load and zero-displacement points and was compared with the tensile stress-strain curve. The yield strengths of the Al-CNT composites from the nanoindentation and tensile tests were compared and discussed. We believe that the yield strength can be predicted using a simple nanoindentation stress/strain curve and that this method will be useful for materials that are difficult to machine, such as complex ceramics.

  19. Damage-tolerant composite materials produced by stitching carbon fibers

    NASA Technical Reports Server (NTRS)

    Dow, Marvin B.; Smith, Donald L.

    1989-01-01

    NASA-Langley has undertaken the investigation of composite damage-tolerance enhancement and fabrication economies-maximization via reinforcement-stitching, in combination with resin transfer molding. Attention is given to results obtained by an experimental evaluation of composites tailored for damage tolerance by stitching layers of dry carbon-fiber fabric with closely-spaced threads, in order to furnish through-the-thickness reinforcement. Various stitching patterns and thread materials have been evaluated, using flat-plate specimens; blade-stiffened structural elements have been fabricated and tested. The results presented indicate that stitched laminates furnish damage tolerance performance comparable to that of more expensive, toughened-matrix composites.

  20. Delamination, durability and damage tolerance of laminated composite materials

    NASA Technical Reports Server (NTRS)

    O'Brien, T. K.

    1991-01-01

    Research exploring the role of delamination on the durability and damage tolerance of advanced composite materials is reviewed. Recent studies on the characterization of composite delamination are summarized. Recent analytical solutions for interlaminar stresses and strain energy release rates associated with common sources of delamination are also reviewed. The role of delamination in low velocity impact, residual compression strength, and in fatigue is highlighted. Delamination is shown to be the common damage mode observed in all of these problems. A Damage Threshold/Fail-safety concept for addressing composite damage tolerance is discussed.

  1. Effective thermal conductivity of a thin, randomly oriented composite material

    SciTech Connect

    Phelan, P.E. [Arizona State Univ., Tempe, AZ (United States). Dept. of Mechanical and Aerospace Engineering; Niemann, R.C. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-10-01

    The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thicknesses. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relative low thermal conductivity. The results indicate that, below some threshold thickness, the composite thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between the filler and matrix thermal conductivities.

  2. Thermal design of composite material high temperature attachments

    NASA Technical Reports Server (NTRS)

    1972-01-01

    An evaluation has been made of the thermal aspects of utilizing advanced filamentary composite materials as primary structures on the shuttle vehicle. The technical objectives of this study are to: (1) establish and design concepts for maintaining material temperatures within allowable limits at TPS attachments and or penetrations applicable to the space shuttle; and (2) verify the thermal design analysis by testing selected concepts. Specific composite materials being evaluated are boron epoxy, graphite/epoxy, boron polyimide, and boron aluminum; graphite/polyimide has been added to this list for property data identification and preliminary evaluation of thermal design problems. The TPS standoff to composite structure attachment over-temperature problem is directly related to TPS maximum surface temperature. To provide a thermally comprehensive evaluation of attachment temperature characteristics, maximum surface temperatures of 900 F, 1200 F, 1800 F, 2500 F and 3000 F are considered in this study. This range of surface temperatures and the high and low maximum temperature capability of the selected composite materials will result in a wide range of thermal requirements for composite/TPS standoff attachments.

  3. Highly explosive nanosilicon-based composite materials

    NASA Astrophysics Data System (ADS)

    Clément, D.; Diener, J.; Gross, E.; Künzner, N.; Timoshenko, V. Yu.; Kovalev, D.

    2005-06-01

    We present a highly explosive binary system based on porous silicon layers with their pores filled with solid oxidizers. The porous layers are produced by a standard electrochemical etching process and exhibit properties that are different from other energetic materials. Its production is completely compatible with the standard silicon technology and full bulk silicon wafers can be processed and therefore a large number of explosive elements can be produced simultaneously. The application-relevant parameters: the efficiency and the long-term stability of various porous silicon/oxidizer systems have been studied in details. Structural properties of porous silicon, its surface termination, the atomic ratio of silicon to oxygen and the chosen oxidizers were optimized to achieve the highest efficiency of the explosive reaction. This explosive system reveals various possible applications in different industrial fields, e.g. as a novel, very fast airbag igniter.

  4. Fracture toughness of fibrous composite materials

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1984-01-01

    Laminates with various proportions of 0 deg, 45 deg, and 90 deg plies were fabricated from T300/5208 and T300/BP-907 graphite/epoxy prepreg tape material. The fracture toughness of each laminate orientation or lay-up was determined by testing center-cracked specimens, and it was also predicted with the general fracture-toughness parameter. The predictions were good except when crack-tip splitting was large, at which time the toughness and strengths tended to be underpredicted. By using predictions, a parametric study was also made of factors that influence fracture toughness. Fiber and matrix properties as well as lay-up were investigated. Without crack-tip splitting, fracture toughness increases in proportion to fiber strength and fiber volume fraction, increases linearly with E(22)/E(11), is largest when the modulus for non-0 deg fibers is greater than that of 0 deg fibers, and is smallest for 0(m)/90(p)(s) lay-ups. (The E(11) and E(22) are Young's moduli of the lamina parallel to and normal to the direction of the fibers, respectively). For a given proportion of 0 deg plies, the most notch-sensitive lay-ups are 0(m)/90(p)(s) and the least sensitive are 0(m)/45(n)(s) and alpha(s). Notch sensitivity increases with the proportion of 0 deg plies and decreases with alpha. Strong, tough matrix materials, which inhibit crack-tip splitting, generally lead to minimum fracture toughness.

  5. Self-healing bentonite sheet material composite drainage structure

    SciTech Connect

    Harriett, T.D.

    1988-03-29

    A composite drainage structure capable of directing water longitudinally away from a potential area of water flow and incapable of transverse water penetration is described comprising: drainage means for receiving water and channeling the water to a predetermined area; channel means disposed between the first and second sheet materials of the drainage means for channeling water longitudinal within the drainage means to the predetermined area; and a cohesive layer of a water-swellable clay composition secured to the water-impermeable layer of sheet material.

  6. Nondestructive inspection and evaluation of composite-material flywheels

    SciTech Connect

    Boyd, D M; Maxfield, B W; Kulkarni, S V; Schwarber, A J

    1982-02-24

    Several composite panels and flywheel designs were evaluated in support of the Mechanical Energy Storage Technology (MEST) project. Conventional nondestructive evaluation (NDE) technology was used on the panels and flywheels. All flywheels and panels were radiographed and, where practical, were also inspected using ultrasonic techniques. The results provided information about the structural features of flywheels and materials. This information is useful for the quality control of fabrication procedures. The detection of apparent flaws in fabrication cannot be related to the ultimate strength until failure mechanisms in composite materials have been fully defined. Therefore, the location of detected flaws should be recorded for later comparison with dynamic and destructive evaluations.

  7. Natural and technologic hazardous material releases during and after natural disasters: a review

    Microsoft Academic Search

    Stacy Young; Lina Balluz; Josephine Malilay

    2004-01-01

    Natural disasters may be powerful and prominent mechanisms of direct and indirect hazardous material (hazmat) releases. Hazardous materials that are released as the result of a technologic malfunction precipitated by a natural event are referred to as natural-technologic or na-tech events. Na-tech events pose unique environmental and human hazards. Disaster-associated hazardous material releases are of concern, given increases in population

  8. Physical properties of three packable resin-composite restorative materials.

    PubMed

    Kelsey, W P; Latta, M A; Shaddy, R S; Stanislav, C M

    2000-01-01

    This study evaluated selected physical properties of three packable resin composites (Alert, SureFil and Solitaire) and compared them to two conventional hybrid materials (Prodigy and Z-100). The specific properties investigated were diametral tensile strength, transverse strength, elastic modulus and fracture toughness. Following photopolymerization, specimens for each composite material were stored in deionized water at 37 degrees C for 35 days. A one-way ANOVA and Tukey's post-hoc test were employed for each property to determine whether significant differences occurred with respect to specific restorative materials. All materials had statistically similar diametral tensile strengths. Alert had the highest mean fracture toughness and elastic modulus but had a low mean transverse-strength value. SureFil exhibited good mean physical property values compared to both the conventional and packable materials. Solitaire had low mean fracture toughness, transverse strength and elastic modulus values, which could cause concern regarding use in posterior restorations. The packable resin composites tested had a wide range of mean values for the physical properties investigated. Generally, Alert and SureFil were superior to Solitaire and comparable to the hybrid materials Prodigy and Z-100, but clear discrimination among performance of these materials requires clinical testing. PMID:11203839

  9. Graphene and carbon nanofiber nanopaper for multifunction composite materials

    NASA Astrophysics Data System (ADS)

    Wu, Chunxia; Lu, Haibao; Liu, Liwu; Liu, Yanju; Leng, Jinsong

    2011-04-01

    The new structures and multifunctional materials is that it can achieve some other special functions while it has ability to carry, such as wave-transparent, absorbing, anti-lightning, anti-heat, anti-nuclear etc. It represents the direction of future development of structural materials. And graphene is the one of two-dimensional atomic crystal free substance only found in the existence and shows great importance for fundamental studies and technological applications due to its unique structure and a wide range of unusual properties. It exhibits great promise for potential applications in chemistry, materials, and many other technological fields. In this paper, we prepare nanopaper through physical vapor deposition (PVD) with a variety in the weight ratio between graphene and nanofiber. Then prepare composite materials with nanopaper and T300/AG80 prepreg by the meaning of autoclave molding. The morphology of nanopaper was characterized by transmission electron microscopy (TEM) and scanning electron microscope (SEM). And the electrical properties and the EMI shielding performances of these nanocomposites have been investigated experimentally by and four-point probe measurement and vector network analyzer. The experimental results indicate that the composites made from graphene and nanofiber nanopaper have highly electric capability, and the EMI shielding value of composites were all up to -15dB. In the same time the conductivity and the EMI shielding performances were improved with increasing the ratio of graphene in nanopaper. We tested the mechanical properties of composite materials at the same time. The average strength of composite materials is about 2000MPa, the elastic modulus is 130GPa above. We are sure that it can be used as the load-bearing structural material which has a multi-functional performance in the aviation field.

  10. A thermodynamical constitutive model for shape memory materials. Part II. The SMA composite material

    Microsoft Academic Search

    James G. Boyd; Dimitris C. Lagoudas

    1996-01-01

    The phenomenological SMA equations developed in Part I are used in this second paper to derive the free energy and dissipation of a SMA composite material. The derivation consists of solving a boundary value problem formulated over a mesoscale representative volume element, followed by an averaging procedure to obtain the macroscopic composite constitutive equations. Explicit equations are derived for the

  11. Experimental determination of material constants of a hybrid composite laminate

    SciTech Connect

    Ihekweazu, S.N.; Lari, S.B.; Unanwa, C.O. [South Carolina State Univ., Orangeburg, SC (United States)

    1999-07-01

    This paper discusses the results of the experimental study that was conducted in order to determine the material properties of a hybrid composite laminate made from Fiberite material MXM-7714/120 (a fabric prepreg consisting of woven Kevlar{reg_sign} 49 reinforcement impregnated with Fiberite 250 F (121 C) curing 7714 epoxy resin) and HYE-2448AIE (a 250 F (121 C) curing epoxy resin impregnated unidirectional graphite tape). First, each of the materials that comprise the hybrid laminate was fabricated separately according to ASTM-D-3039 specification in order to determine their material properties. The materials were then hybridized and the properties were determined. Data from this experiment reveal that a new class of material that can meet desired specifications can be created through hybridization. The data also revealed that the properties of the materials bonded together as a hybrid complement the properties of the constituent members of the hybrid.

  12. Compositional Analysis of Water-Soluble Materials in Corn Stover

    Microsoft Academic Search

    Shou-Feng Chen; Richard A. Mowery; Christopher J. Scarlata; C. Kevin Chambliss

    2007-01-01

    Corn stover is one of the leading feedstock candidates for commodity-scale biomass-to-ethanol processing. The composition of water-soluble materials in corn stover has been determined with greater than 90% mass closure in four of five representative samples. The mass percentage of water-soluble materials in tested stover samples varied from 14 to 27% on a dry weight basis. Over 30 previously unknown

  13. Damorheology: Creep-fatigue interaction in composite materials

    Microsoft Academic Search

    Osiroff

    1990-01-01

    The interaction mechanisms of time dependent material behavior and cyclic damage during fatigue loading of fiber reinforced composite laminates are addressed. A new term, damorheology, was coined to describe such physical behavior. The lamina was chosen as the building block and a cross ply laminate configuration was the selected test case. The chosen material system is the Radel X\\/T65-42 thermoplastic

  14. Structure and properties of aluminum bronze-lead composite material

    Microsoft Academic Search

    V. S. Voropaev; G. Y. Kalutskii

    1999-01-01

    The effect of sintering regime on the structure and properties of aluminum bronze-lead composite material is studied by experiment.\\u000a It is established that in order to prepare material with a uniform lead distribution and high mechanical properties the sintering\\u000a duration should not exceed 5 min. More prolonged heat treatment leads to redistribution of lead with formation of a coarse-grained\\u000a structure

  15. Material degradation assessment for stiffened composite shells using metamodelling approach

    Microsoft Academic Search

    Kaspars Kalnins; Rolands Rikards; Janis Auzins

    The intense interest coming from the aerospace industry indicates the need of safe exploitation of composite materials in\\u000a stiffened shell structures. Since stiffened shells are far most consumed structural component, it is important to study the\\u000a behaviour of material degradation to evaluate the safe design guidelines. Moreover, current numerical procedures cannot simulate\\u000a the collapse of stiffened shells with sufficient reliability

  16. Transverse thermal conductance of thermosetting composite materials during their cure

    Microsoft Academic Search

    Jeffrey D. Farmer; Eugene E. Covert

    1994-01-01

    The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4\\/3501-6 graphite\\/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh, was modified to account for the possible effects of a fiber\\/resin contact resistance

  17. Transverse thermal conductance of thermosetting composite materials during their cure

    Microsoft Academic Search

    J. D. Farmer; E. E. Covert

    1993-01-01

    The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4\\/3501-6 graphite\\/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh was modified to account for the possible effects of a fiber\\/resin contact resistance

  18. Fire characteristics of cored composite materials for marine use

    Microsoft Academic Search

    Nicholas A. Dembsey; Jonathan R. Barnett

    1998-01-01

    This paper presents results from Cone Calorimeter testing of two types of cored composite materials used in shipbuilding: a GRP\\/Balsa-cored sandwich and a GRP\\/PVC foam-cored sandwich. The observed phenomena of delamination, melting and charring of the core materials, and edge effects are discussed in the context of how they affect test results. The “standard” ignition data analysis method specified in

  19. Simulation of ultrasonic array imaging of composite materials with defects.

    PubMed

    Humeida, Yousif; Pinfield, Valerie J; Challis, Richard E; Wilcox, Paul D; Li, Chuan

    2013-09-01

    Ultrasonic transducer arrays are extensively used for the nondestructive evaluation of materials for aerospace and other applications. However, their use with composites requires some technique development because of reflections at the layer boundaries and the effects of attenuation. When used in full matrix capture mode, algorithms such as the total focusing method (TFM) must be applied to obtain the image. In composite materials, improvement to the algorithm is required to include the effects of material anisotropy (affecting wave speed) and optimum aperture limits to optimize the signal-to-noise ratio and location detection for a defect in the material. This paper presents simulations of the ultrasonic array signals in multilayer anisotropic materials with and without a simulated defect. A kernel model for plane wave propagation in the material is combined with an angular spectrum decomposition (for finite transducer elements) and transducer frequency response, to model the full array signals. Inclusion of the defect is through its far-field scattering response. The model facilitates the study of imaging algorithm development by identification of the effects of anisotropy, signal-to-noise ratio, and aperture limit. An analytical method for the calculation of the effective group velocity in the composite at low frequency is demonstrated, permitting rapid calculation of time delay laws in practice. PMID:24658724

  20. Novel Microstructures for Polymer-Liquid Crystal Composite Materials

    NASA Technical Reports Server (NTRS)

    Magda, Jules J.

    2004-01-01

    There are a number of interface-dominated composite materials that contain a liquid crystalline (LC) phase in intimate contact with an isotropic phase. For example, polymer- dispersed liquid crystals, used in the fabrication of windows with switchable transparency, consist of micron size LC droplets dispersed in an isotropic polymer matrix. Many other types of liquid crystal composite materials can be envisioned that might have outstanding optical properties that could be exploited in novel chemical sensors, optical switches, and computer displays. This research project was based on the premise that many of these potentially useful LC composite materials can only be fabricated under microgravity conditions where gravity driven flows are absent. In the ground-based research described below, we have focused on a new class of LC composites that we call thermotropic- lyotropic liquid crystal systems (TLLCs). TLLCs consist of nanosize droplets of water dispersed in an LC matrix, with surfactants at the interface that stabilize the structure. By varying the type of surfactant one can access almost an infinite variety of unusual LC composite microstructures. Due to the importance of the interface in these types of systems, we have also developed molecular simulation models for liquid crystals at interfaces, and made some of the first measurements of the interfacial tension between liquid crystals and water.

  1. Structure of boundaries in composite materials obtained using explosive loading

    NASA Astrophysics Data System (ADS)

    Lysak, V. I.; Kuz'min, S. V.; Krokhalev, A. V.; Grinberg, B. A.

    2013-11-01

    We have presented the results of studying the fine structure of interphase boundaries for a number of composite materials obtained by methods of explosive welding and explosive compacting of powder mixtures. Joints of different metals (titanium-low-carbon steel, copper-tantalum) and metals with refractory carbides (chromium carbide-titanium) have been investigated. Under welding, pairs differed from each other by the type of interaction. It has been found that, in these composites, interphase boundaries exhibit a final thickness on the order of 200 nm, throughout which the composition of the material changes gradually from a composition that corresponds to one of the components of the composite to a composition that corresponds to the second component. It has been shown that the structure of interphase boundaries is complex. With the limited solubility of components along boundaries, two fairly thick crystalline interlayers are detected, the total thickness of which is equal to the total thickness of the boundary; between the interlayers, there is a thin (to 5-7 nm in thickness) interlayer with a crystalline or amorphous structure.

  2. ADSORPTION OF ORGANIC CATIONS TO NATURAL MATERIALS

    EPA Science Inventory

    The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. The sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concentrations of NaCl and CaCl,...

  3. ADSORPTION OF ORGANIC CATIONS TO NATURAL MATERIALS

    EPA Science Inventory

    The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. he sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concentrations of NaCl and CaC12,...

  4. The Natural Materials Browser: Using a Tablet Interface for Exploring Volumetric Materials Science Datasets

    E-print Network

    Hollerer, Tobias

    The Natural Materials Browser: Using a Tablet Interface for Exploring Volumetric Materials Science angus.forbes@sista.arizona.edu Tony Fast Department of Materials Science Georgia Institute of Technology]: Methodologies and Techniques--interaction techniques 1 INTRODUCTION & RELATED WORK In materials science

  5. Compendium of Material Composition Data for Radiation Transport Modeling

    SciTech Connect

    Williams, Ralph G.; Gesh, Christopher J.; Pagh, Richard T.

    2006-10-31

    Computational modeling of radiation transport problems including homeland security, radiation shielding and protection, and criticality safety all depend upon material definitions. This document has been created to serve two purposes: 1) to provide a quick reference of material compositions for analysts and 2) a standardized reference to reduce the differences between results from two independent analysts. Analysts are always encountering a variety of materials for which elemental definitions are not readily available or densities are not defined. This document provides a location where unique or hard to define materials will be located to reduce duplication in research for modeling purposes. Additionally, having a common set of material definitions helps to standardize modeling across PNNL and provide two separate researchers the ability to compare different modeling results from a common materials basis.

  6. Fractography of modern engineering materials: Composites and metals, Second volume

    SciTech Connect

    Masters, J.E.; Gilbertson, L.N. (eds.)

    1993-01-01

    This book contains the manuscripts of eleven papers that were presented at the Second Symposium on Fractography of Modern Engineering Materials held in May 1992. The numerous advances in materials science in the six year period following the First Symposium dictated this second meeting. Not only had new materials been developed in the intervening years, but understanding of older materials had also progressed. Similarly, advances in the technology and the techniques of fractography had occurred. The objective of the symposium was to extend the colloquy on fractography to include these many advances. The paper may be divided into three sections: Unique Fractographic Techniques; Metallic Materials; Polymeric and Composite Materials. The section titles reflect the diversity of materials discussed in the meeting. The range of materials included cross-linked polyethylene, AISI 52100 steel, 2024 aluminum, and a variety of organic and metal matrix fibrous composites. The case studies presented also covered a wide range. They included failure investigations of an antenna used in deep space exploration and chemical storage tanks. Advances in the techniques of fractography were also reflected in a number of presentations; quantitative techniques and expert systems were also subjects of presentations. A short precis of each paper is included here to assist the readers in identifying works of particular interest.

  7. Transverse thermal conductance of thermosetting composite materials during their cure

    NASA Astrophysics Data System (ADS)

    Farmer, Jeffrey D.; Covert, Eugene E.

    1994-04-01

    The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4/3501-6 graphite/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh, was modified to account for the possible effects of a fiber/resin contact resistance and for the transversely anisotropic behavior of the composites' thermal conductivity. A model was derived that accounts for the effect of resin heat generation on the measured thermal conductivity of an uncured thermosetting composite. These models were investigated experimentally using a guarded hot plate apparatus to measure the thermal conductivity of the graphite/epoxy laminates as a function of independent cure variables. Good agreement was found between the models and the experimental data.

  8. Data-mined similarity function between material compositions

    NASA Astrophysics Data System (ADS)

    Yang, Lusann; Ceder, Gerbrand

    2013-12-01

    A new method for assessing the similarity of material compositions is described. A similarity measure is important for the classification and clustering of compositions. The similarity of the material compositions is calculated utilizing a data-mined ionic substitutional similarity based upon the probability with which two ions will substitute for each other within the same structure prototype. The method is validated via the prediction of crystal structure prototypes for oxides from the Inorganic Crystal Structure Database, selecting the correct prototype from a list of known prototypes within five guesses 75% of the time. It performs particularly well on the quaternary oxides, selecting the correct prototype from a list of known prototypes on the first guess 65% of the time.

  9. The behavior of sandwich structures of isotropic and composite materials

    Microsoft Academic Search

    J. R. Vinson

    1999-01-01

    The Behavior of Sandwich Structures of Isotropic and Composite Materials provides a unique presentation of mathematics, descriptions and analysis of techniques in the growing field of sandwich structures. Everything is covered, from a background of sandwich structures, to thermoelastic problems of sandwich structures, sandwich shell theory and much more. This test is ideal for the engineer-in-training, as well as the

  10. Optimal experimental design for estimating thermal properties of composite materials

    Microsoft Academic Search

    R. Taktak; J. V. Beck; E. P. Scott

    1993-01-01

    Design of optimal transient experiments is needed for the efficient estimation of thermal conductivity and volumetric heat capacity of composite materials. One criterion for optimal experiments is the minimization of the area (or volume) of the confidence region. The experimental designs are transient and involve both finite and semi-finite geometries with finite duration heating. Two cases are considered for the

  11. Tungsten filament as reinforcement for heat resistant composite materials

    Microsoft Academic Search

    N. M. Fonshtein; G. N. Tikhomirova; V. F. Kotov; V. I. Shvarts

    1971-01-01

    Fine tungsten filament is a promising reinforcement for composite materials. This is due to the good properties of alloys based on tungsten - high recrystallizatio n temperature, high strength and modulus of elasticity in a fairly wide temperature range, and, particularly valuable, deformability of a continuous filament with a diameter from a few microns to several millimeters. Thin filaments are

  12. NASA Composite Materials Development: Lessons Learned and Future Challenges

    NASA Technical Reports Server (NTRS)

    Tenney, Darrel R.; Davis, John G., Jr.; Pipes, R. Byron; Johnston, Norman

    2009-01-01

    Composite materials have emerged as the materials of choice for increasing the performance and reducing the weight and cost of military, general aviation, and transport aircraft and space launch vehicles. Major advancements have been made in the ability to design, fabricate, and analyze large complex aerospace structures. The recent efforts by Boeing and Airbus to incorporate composite into primary load carrying structures of large commercial transports and to certify the airworthiness of these structures is evidence of the significant advancements made in understanding and use of these materials in real world aircraft. NASA has been engaged in research on composites since the late 1960 s and has worked to address many development issues with these materials in an effort to ensure safety, improve performance, and improve affordability of air travel for the public good. This research has ranged from synthesis of advanced resin chemistries to development of mathematical analyses tools to reliably predict the response of built-up structures under combined load conditions. The lessons learned from this research are highlighted with specific examples to illustrate the problems encountered and solutions to these problems. Examples include specific technologies related to environmental effects, processing science, fabrication technologies, nondestructive inspection, damage tolerance, micromechanics, structural mechanics, and residual life prediction. The current state of the technology is reviewed and key issues requiring additional research identified. Also, grand challenges to be solved for expanded use of composites in aero structures are identified.

  13. Making Composite-Material Parts At Moderate To High Rates

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1995-01-01

    Composite-material (matrix/fiber) structural components manufactured at moderate to high rates in production-line-style processes, according to proposal. In method, production lines largely automated and takes advantage of fact matrix resins cured by electron beams in addition to heat. Net result reductions in production times and costs.

  14. Development of a pultruded composite material highway guardrail

    Microsoft Academic Search

    L. C Bank; T. R Gentry

    2001-01-01

    Fiber-reinforced polymer (FRP) composite materials are being used to develop products for use as highway appurtenances, such as, sign supports, luminaire supports and guardrails (crash barriers). These structures, that are located alongside highways and roads, are subjected to vehicular impacts and must be designed to be ‘crashworthy’ to ensure the safety of the driving public. This paper reviews an ongoing

  15. Composite materials for roller electrodes in electromechanical treatment

    Microsoft Academic Search

    P. Ya. Pavlikov; G. G. Gnesin; A. A. Flis; V. D. Valentinov; B. M. Politov

    1989-01-01

    Electromechanical treatment with roller electrodes produced from a tungsten-base composite material with additions of copper and alloy elements made it possible to increase the wear resistance of gas turbine engine parts operating under conditions of sliding friction. Such parts are, for example, reducer bearing pillow block housings made of alloy steels, pinion shafts for oil pump drives, spindles of metal

  16. Numerical Simulation of Delamination Growth in Composite Materials

    Microsoft Academic Search

    P. P. Camanho; D. R. Ambur

    2001-01-01

    Abstract The use of decohesion elements for the simulation of delamination in composite materials is reviewed The test methods available to measure the interfacial fracture toughness used in the formulation of decohesion elements are described initially After a brief presentation of the virtual crack closure technique, the technique most widely used to simulate delamination growth, the formulation of interfacial decohesion

  17. Energy Harvesting Devices Using Macro-fiber Composite Materials

    Microsoft Academic Search

    Hyun Jeong Song; Young-Tai Choi; Norman M. Wereley; Ashish S. Purekar

    2010-01-01

    This study addresses the experimental validation of a design methodology for an energy harvesting device utilizing macro-fiber composite (MFC) materials. The energy harvesting device is composed of a cantilever beam with MFC elements, a tip mass, a rectifier, and an electrical resistance. A theoretical model of the energy harvesting device was developed for the estimation of generated power, voltage, and

  18. Genetic optimization of two-material composite laminates Laurent Grosset

    E-print Network

    Coello, Carlos A. Coello

    Genetic optimization of two-material composite laminates Laurent Grosset , Satchi Venkataraman@aero.ufl.edu) Post-Doctoral Associate (satchi@aero.ufl.edu) Distinguished Professor, Fellow AIAA (haftka & Engineering Science, University of Florida, P.O.Box 116250, Gainesville, FL 32611, USA Satchi Venkataraman

  19. Impact damage detection of composite materials by fiber Bragg gratings

    Microsoft Academic Search

    Zoran Djinovic; Michael Scheerer; Milos Tomic

    2011-01-01

    Usage of fiber-optic Bragg gratings (FBG) for strain measurement is well-known technique in structural health monitoring (SHM). However, this technique based on shift of spectral peak, suffers from different spurious signals, particularly caused by thermal effect. We present here a method for impact damage detection of composite materials based on FBG without thermal disturbance. This method is based on the

  20. Development of rice husks-plastics composites for building materials.

    PubMed

    Choi, Nak-Woon; Mori, Ippei; Ohama, Yoshihiko

    2006-01-01

    In this paper, a new effective recycling method for rice husks and waste expanded polystyrene is developed by using a combination of both wastes. A styrene solution of waste expanded polystyrene is used as a binder for rice husks-plastics composites. The composites are prepared with various mix proportions by a hot press molding method, and tested for apparent density, water absorption, expansion in thickness, and dry and wet flexural strengths. From the test results, the apparent density of the composites is increased with increasing binder content and filler-binder ratio. Their flexural strength and wet flexural strengths reach maximums at a binder content of 30.0% and a filler-binder ratio of 1.0. Their water absorption and expansion in thickness are decreased with increasing binder content and filler-binder ratio. Since the composites have a high flexural strength and water resistance, their uses as building materials are expected. PMID:16256327

  1. Computational design and optimization of a biomimetic self-healing\\/cooling composite material

    Microsoft Academic Search

    Alejandro M. Aragón; Christopher J. Hansen; Willie Wu; Philippe H. Geubelle; Jennifer Lewis; Scott R. White

    2007-01-01

    Inspired by natural examples of microvascular systems in a wide variety of living organisms, we perform the computational design of a new class of polymer-based composite materials with the unique ability to heal and\\/or cool in a completely autonomic fashion, i.e., without any external intervention. The design process combines graph theory to represent and evaluate the microvascular network and Genetic

  2. Interdisciplinary research concerning the nature and properties of ceramic materials

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The nature and properties of ceramic materials as they relate to solid state physics and metallurgy are studied. Special attention was given to the applications of ceramics to NASA programs and national needs.

  3. Trihalomethanes formed from natural organic matter isolates: Using isotopic and compositional data to help understand sources

    USGS Publications Warehouse

    Bergamaschi, B.A.; Fram, M.S.; Fujii, R.; Aiken, G.R.; Kendall, C.; Silva, S.R.

    2000-01-01

    Over 20 million people drink water from the Sacramento-San Joaquin Delta despite problematic levels of natural organic matter (NOM) and bromide in Delta water, which can form trihalomethanes (THMs) during the treatment process. It is widely believed that NOM released from Delta peat islands is a substantial contributor to the pool of THM precursors present in Delta waters. Dissolved NOM was isolated from samples collected at five channel sites within the Sacramento-San Joaquin Rivers and Delta, California, USA, and from a peat island agricultural drain. To help understand the sources of THM precursors, samples were analyzed to determine their chemical and isotopic composition, their propensity to form THMs, and the isotopic composition of the THMs. The chemical composition of the isolates was quite variable, as indicated by significant differences in carbon-13 nuclear magnetic resonance spectra and carbon-to-nitrogen concentration ratios. The lowest propensity to form THMs per unit of dissolved organic carbon was observed in the peat island agricultural drain isolate, even though it possessed the highest fraction of aromatic material and the highest specific ultraviolet absorbance. Changes in the chemical and isotopic composition of the isolates and the isotopic composition of the THMs suggest that the source of the THMs precursors was different between samples and between isolates. The pattern of variability in compositional and isotopic data for these samples was not consistent with simple mixing of river- and peat-derived organic material.

  4. nature materials | VOL 6 | OCTOBER 2007 | www.nature.com/naturematerials 723 REVIEW ARTICLE

    E-print Network

    Krasheninnikov, Arkady V.

    the irradiation-induced degradation of components of nuclear fission or fusion reactors1nature materials | VOL 6 | OCTOBER 2007 | www.nature.com/naturematerials 723 REVIEW ARTICLE A. V creates defects and thus deteriorates the materials. Indeed, the first motivation for studying how

  5. Investigation of low velocity impact damage on filamentary composite materials

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1987-01-01

    Presented are the results of an investigation of the effect of low velocity impact on the residual modulus and residual strength of flat filamentary composite materials. Theoretical analysis of composite materials indicates that the modulus of the material must decrease as impact damage increases. This decrease must also correlate to the decrease in residual strength. This study attempts to verify these hypotheses. Graphite/epoxy laminates (AS4/3501-6) of various fiber orientations (8 (0 deg), 2 (+ or - 45 deg)sub 8) were impacted using a falling weight impact tester. Impact energies ranged from 0.42 to 1.55 ft-lb, with impact velocities from 2.03 to 3.98 ft/sec. The results show that there is a reduction in residual modulus of the plate as the impact energy increases.

  6. High resolution computed tomography of advanced composite and ceramic materials

    NASA Technical Reports Server (NTRS)

    Yancey, R. N.; Klima, S. J.

    1991-01-01

    Advanced composite and ceramic materials are being developed for use in many new defense and commercial applications. In order to achieve the desired mechanical properties of these materials, the structural elements must be carefully analyzed and engineered. A study was conducted to evaluate the use of high resolution computed tomography (CT) as a macrostructural analysis tool for advanced composite and ceramic materials. Several samples were scanned using a laboratory high resolution CT scanner. Samples were also destructively analyzed at the locations of the scans and the nondestructive and destructive results were compared. The study provides useful information outlining the strengths and limitations of this technique and the prospects for further research in this area.

  7. The weak interfaces within tough natural composites: experiments on three types of nacre.

    PubMed

    Khayer Dastjerdi, Ahmad; Rabiei, Reza; Barthelat, Francois

    2013-03-01

    Mineralization is a typical strategy used in natural materials to achieve high stiffness and hardness for structural functions such as skeletal support, protection or predation. High mineral content generally leads to brittleness, yet natural materials such as bone, mollusk shells or glass sponge achieve relatively high toughness considering the weakness of their constituents through intricate microstructures. In particular, nanometers thick organic interfaces organized in micro-architectures play a key role in providing toughness by various processes including crack deflection, crack bridging or energy dissipation. While these interfaces are critical in these materials, their composition, structure and mechanics is often poorly understood. In this work we focus on nacre, one of the most impressive hard biological materials in terms of toughness. We performed interfacial fracture tests on chevron notched nacre samples from three different species: red abalone, top shell and pearl oyster. We found that the intrinsic toughness of the interfaces is indeed found to be extremely low, in the order of the toughness of the mineral inclusions themselves. Such low toughness is required for the cracks to follow the interfaces, and to deflect and circumvent the mineral tablets. This result highlights the efficacy of toughening mechanisms in natural materials, turning low-toughness inclusions and interfaces into high-performance composites. We found that top shell nacre displayed the highest interfacial toughness, because of higher surface roughness and a more resilient organic material, and also through extrinsic toughening mechanisms including crack deflection, crack bridging and process zone. In the context of biomimetics, the main implication of this finding is that the interface in nacre-like composite does not need to be tough; the extensibility or ductility of the interfaces may be more important than their strength and toughness to produce toughness at the macroscale. PMID:23084045

  8. Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures

    NASA Technical Reports Server (NTRS)

    McManus, Hugh L.; Chamis, Christos C.

    1996-01-01

    This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) is presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.

  9. Composite materials. Volume 1: Properties, non-destructive testing, and repair

    Microsoft Academic Search

    1997-01-01

    This book provides a practical overview of the different types, properties, applications and design implementations of the latest composite materials. It describes important composite families, including metals, ceramics, polymers and other engineered materials; shows how each type of composite may be designed, manufactured, strengthened, and repaired; introduces composite modeling techniques; and explains the major industrial applications for composites. Primary markets

  10. Composite materials - fatigue and fracture; Proceedings of the Symposium, Dallas, TX, October 24, 25, 1984

    SciTech Connect

    Hahn, H.T.

    1986-01-01

    The aspects of fracture and fatigue in composite materials are discussed in papers which include dynamic delamination crack propagation in graphite/epoxy laminate, the influence of mold coverage upon the notch strength of R25 sheet molding compounds, interface studies of aluminum metal matrix composites, fatigue behavior of continuous-fiber silicon carbide/aluminum composites, and fatigue damage in notched pultruded composite rods. Attention is also given to the fracture of thick graphite/epoxy laminates with part-through surface flaws, failure analysis of a graphite/epoxy laminate subjected to bolt-bearing loads, probabilistic fracture kinetics of natural composites, and fatigue failure mechanisms in unidirectional composites. Also discussed are internal load distribution effects during the fatigue loading of composite laminates, the interrelationship between fiber fracture and ply cracking in graphite/epoxy laminates, a critical-element model of the residual strength and life of fatigue-loaded composite coupons, the response of thick notched laminates subjected to tension-compression cyclic loads, and the effect of ply thickness on longitudinal splitting and delamination in graphite/epoxy under compressive cyclic load.

  11. Experimental and Analytical Characterization of the Macromechanical Response for Triaxial Braided Composite Materials

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.

    2013-01-01

    Increasingly, carbon composite structures are being used in aerospace applications. Their highstrength, high-stiffness, and low-weight properties make them good candidates for replacing many aerospace structures currently made of aluminum or steel. Recently, many of the aircraft engine manufacturers have developed new commercial jet engines that will use composite fan cases. Instead of using traditional composite layup techniques, these new fan cases will use a triaxially braided pattern, which improves case performance. The impact characteristics of composite materials for jet engine fan case applications have been an important research topic because Federal regulations require that an engine case be able to contain a blade and blade fragments during an engine blade-out event. Once the impact characteristics of these triaxial braided materials become known, computer models can be developed to simulate a jet engine blade-out event, thus reducing cost and time in the development of these composite jet engine cases. The two main problems that have arisen in this area of research are that the properties for these materials have not been fully determined and computationally efficient computer models, which incorporate much of the microscale deformation and failure mechanisms, are not available. The research reported herein addresses some of the deficiencies present in previous research regarding these triaxial braided composite materials. The current research develops new techniques to accurately quantify the material properties of the triaxial braided composite materials. New test methods are developed for the polymer resin composite constituent and representative composite coupons. These methods expand previous research by using novel specimen designs along with using a noncontact measuring system that is also capable of identifying and quantifying many of the microscale failure mechanisms present in the materials. Finally, using the data gathered, a new hybrid micromacromechanical computer model is created to simulate the behavior of these composite material systems under static and ballistic impact loading using the test data acquired. The model also quantifies the way in which the fiber/matrix interface affects material response under static and impact loading. The results show that the test methods are capable of accurately quantifying the polymer resin under a variety of strain rates and temperature for three loading conditions. The resin strength and stiffness data show a clear rate and temperature dependence. The data also show the hydrostatic stress effects and hysteresis, all of which can be used by researchers developing composite constitutive models for the resins. The results for the composite data reveal noticeable differences in strength, failure strain, and stiffness in the different material systems presented. The investigations into the microscale failure mechanisms provide information about the nature of the different material system behaviors. Finally, the developed computer model predicts composite static strength and stiffness to within 10 percent of the gathered test data and also agrees with composite impact data, where available.

  12. Percolation modeling of self-damaging of composite materials

    NASA Astrophysics Data System (ADS)

    Domanskyi, Sergii; Privman, Vladimir

    2014-07-01

    We propose the concept of autonomous self-damaging in “smart” composite materials, controlled by activation of added nanosize “damaging” capsules. Percolation-type modeling approach earlier applied to the related concept of self-healing materials, is used to investigate the behavior of the initial material's fatigue. We aim at achieving a relatively sharp drop in the material's integrity after some initial limited fatigue develops in the course of the sample's usage. Our theoretical study considers a two-dimensional lattice model and involves Monte Carlo simulations of the connectivity and conductance in the high-connectivity regime of percolation. We give several examples of local capsule-lattice and capsule-capsule activation rules and show that the desired self-damaging property can only be obtained with rather sophisticated “smart” material's response involving not just damaging but also healing capsules.

  13. Test Report: Direct and Indirect Lightning Effects on Composite Materials

    NASA Technical Reports Server (NTRS)

    Evans, R. W.

    1997-01-01

    Lightning tests were performed on composite materials as a part of an investigation of electromagnetic effects on the materials. Samples were subjected to direct and remote simulated lightning strikes. Samples included various thicknesses of graphite filament reinforced plastic (GFRP), material enhanced by expanded aluminum foil layers, and material with an aluminum honeycomb core. Shielding properties of the material and damage to the sample surfaces and joints were investigated. Adding expanded aluminum foil layers and increasing the thickness of GFRP improves the shielding effectiveness against lightning induced fields and the ability to withstand lightning strikes. A report describing the lightning strike tests performed by the U.S. Army Redstone Technical Test Center, Redstone Arsenal, AL, STERT-TE-E-EM, is included as an appendix.

  14. Femtosecond pulse visible laser processing of fibre composite materials

    NASA Astrophysics Data System (ADS)

    Krüger, Jörg; Kautek, Wolfgang

    1996-10-01

    A first investigation on the ablation of composite materials like carbon and silicon-carbide reinforced alumo- and borosilicate glasses by 300 fs laser pulses (620 nm) in comparison to experiments with 17 ns pulse excimer laser (308 nm) treatment is presented. In all composites, femtosecond laser scans with a fluence of less than 2 J cm -2 produce well defined cuts with smooth side walls in contrast to the nanosecond laser result where extremely incongruent ablation is observed. Visible lasers should not be applicable because SiC and the glasses are practically transparent. Visible subpicosecond pulses of high intensity in the TW cm -2 range allow multi-photon absorption accompanied by incubation phenomena. The morphology of the groove edges reveal the contrasting ablation thresholds and rates of the fibre and glass materials. The ablation thresholds of the transparent components, i.e. the glass matrices and SiC, are about one order of magnitude greater than that of carbon which is ˜ 0.15 J cm -2. Incubation effects are important for the absorption mechanisms in the transparent materials. When a critical number of pulses has not been reached at the SiC-glass composites, only the glass is preferentially ablated, and the fibres remain intact. This is in contrast to the C-glass composites where the ablation behaviour is opposite.

  15. Cellulose nanocrystals, nanofibers, and their composites as renewable smart materials

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Zhai, Lindong; Mun, Seongcheol; Ko, Hyun-U.; Yun, Young-Min

    2015-04-01

    Cellulose is one of abundant renewable biomaterials in the world. Over 1.5 trillion tons of cellulose is produced per year in nature by biosynthesis, forming microfibrils which in turn aggregate to form cellulose fibers. Using new effective methods these microfibrils can be disintegrated from the fibers to nanosized materials, so called cellulose nanocrystal (CNC) and cellulose nanofiber (CNF). The CNC and CNF have extremely good strength properties, dimensional stability, thermal stability and good optical properties on top of their renewable behavior, which can be a building block of new materials. This paper represents recent advancement of cellulose nanocrystals and cellulose nanofibers, followed by their possibility for smart materials. Natural behaviors, extraction, modification of cellulose nanocrystals and fibers are explained and their synthesis with nanomaterials is introduced, which is necessary to meet the technological requirements for smart materials. Also, its challenges are addressed.

  16. Mineralized polymer composites as biogenic bone substitute material

    NASA Astrophysics Data System (ADS)

    Shah, Rushita; Saha, Nabanita; Kitano, Takeshi; Saha, Petr

    2015-05-01

    Mineralized polymer composites (MPC) are recognized as potential fillers of bone defects. Though bioceramics exhibits quite a good bone-bonding and vascularization, it is considered to be too stiff and brittle for using alone. Thus, the use of polymer scaffold instead of bioceramics has several advantages including combining the osteoconductivity and bone-bonding potential of the inorganic phase with the porosity and interconnectivity of the three-dimensional construction. Aiming the advantages of ceramic-polymer composite scaffolds, the calcium carbonate (CaCO3) based biomineralized scaffold was prepared, where the PVP-CMC hydrogel was used as an extracellular matrix. This paper is reported about the morphology, swelling trend (in physiological solution) and viscoelastic behavior of (90 min mineralized) MPC. The dry MPC are off-white, coarse in texture, comparatively less flexible than the original PVP-CMC based hydrogel film, and the deposition of granular structures on the surface of the hydrogel film confirms about the development of biomineralized scaffold/polymer composites. Irrespective of thickness, the dry MPC shows higher values of swelling ratio within 30 min, which varies between 200-250 approximately. The dynamic viscoelastic nature of freshly prepared MPC was investigated applying 1% and 10% strain. At higher strain the viscoelastic moduli (G' and G") show significant change, and the nature of MPC turns from elastic to viscous. Based on the observed basic properties, the MPC (calcite based polymer composites) can be recommended for the treatment of adyanamic bone disorder.

  17. Ultrasonic technique for extracting nanofibers from nature materials

    NASA Astrophysics Data System (ADS)

    Zhao, Hong-Ping; Feng, Xi-Qiao; Gao, Huajian

    2007-02-01

    This letter reports a simple and versatile approach for extracting bionanofibers from natural materials using the ultrasonic technique. Bionanofibers have been fabricated from various materials, e.g., spider and silkworm silks, chitin fibers, collagen, cotton, bamboo, and ramee and hemp fibers. The obtained nanofibers have uniform diameters in the range of 25-120nm and possess the optimized hierarchical structures and superior properties of natural materials which have formed after the evolution of many millions of years. This methodology might be valuable to provide a convenient, versatile, and environmentally benign fabrication method for producing bionanofibers at an industrial scale.

  18. Use of natural raw material for the production of photochromic glasses

    SciTech Connect

    Kiyan, V.I.; Artamonova, M.V.; Solinov, V.F.

    1986-07-01

    The authors investigated the possibility of using natural raw materials as replacements for soda and alumina for obtaining photochromic glasses and to determine their properties. Glasses of the sodium aluminoborosilicate system were studied. The characteristics of the batches and some of the properties of the glasses are given in a table. Sodium oxide was added to batches Nos. 1 and 2 as soda or borax. Composition Nos. 3, 4, and 5 were prepared using acid, basic, and neutral rocks by means of which the oxides of sodium and aluminum were added. The glasses were synthesized in SiC-heater furnaces. The differential thermal analysis of compositions Nos. 1 and 5 showed that the presence of natural materials leads to the formation of a liquid phase at lower temperatures which helps to intensify the processes of silicate- and glass-formation.

  19. Compendium of Material Composition Data for Radiation Transport Modeling

    SciTech Connect

    McConn, Ronald J.; Gesh, Christopher J.; Pagh, Richard T.; Rucker, Robert A.; Williams III, Robert

    2011-03-04

    Introduction Meaningful simulations of radiation transport applications require realistic definitions of material composition and densities. When seeking that information for applications in fields such as homeland security, radiation shielding and protection, and criticality safety, researchers usually encounter a variety of materials for which elemental compositions are not readily available or densities are not defined. Publication of the Compendium of Material Composition Data for Radiation Transport Modeling, Revision 0, in 2006 was the first step toward mitigating this problem. Revision 0 of this document listed 121 materials, selected mostly from the combined personal libraries of staff at the Pacific Northwest National Laboratory (PNNL), and thus had a scope that was recognized at the time to be limited. Nevertheless, its creation did provide a well-referenced source of some unique or hard-to-define material data in a format that could be used directly in radiation transport calculations being performed at PNNL. Moreover, having a single common set of material definitions also helped to standardize at least one aspect of the various modeling efforts across the laboratory by providing separate researchers the ability to compare different model results using a common basis of materials. The authors of the 2006 compendium understood that, depending on its use and feedback, the compendium would need to be revised to correct errors or inconsistencies in the data for the original 121 materials, as well as to increase (per users suggestions) the number of materials listed. This 2010 revision of the compendium has accomplished both of those objectives. The most obvious change is the increased number of materials from 121 to 372. The not-so-obvious change is the mechanism used to produce the data listed here. The data listed in the 2006 document were compiled, evaluated, entered, and error-checked by a group of individuals essentially by hand, providing no library file or mechanism for revising the data in a consistent and traceable manner. The authors of this revision have addressed that problem by first compiling all of the information (i.e., numbers and references) for all the materials into a single database, maintained at PNNL, that was then used as the basis for this document.

  20. DOE/MSU composite material fatigue database: Test methods, materials, and analysis

    SciTech Connect

    Mandell, J.F.; Samborsky, D.D. [Montana State Univ., Bozeman, MT (United States). Dept. of Chemical Engineering

    1997-12-01

    This report presents a detailed analysis of the results from fatigue studies of wind turbine blade composite materials carried out at Montana State University (MSU) over the last seven years. It is intended to be used in conjunction with the DOE/MSU composite Materials Fatigue Database. The fatigue testing of composite materials requires the adaptation of standard test methods to the particular composite structure of concern. The stranded fabric E-glass reinforcement used by many blade manufacturers has required the development of several test modifications to obtain valid test data for materials with particular reinforcement details, over the required range of tensile and compressive loadings. Additionally, a novel testing approach to high frequency (100 Hz) testing for high cycle fatigue using minicoupons has been developed and validated. The database for standard coupon tests now includes over 4,100 data points for over 110 materials systems. The report analyzes the database for trends and transitions in static and fatigue behavior with various materials parameters. Parameters explored are reinforcement fabric architecture, fiber content, content of fibers oriented in the load direction, matrix material, and loading parameters (tension, compression, and reversed loading). Significant transitions from good fatigue resistance to poor fatigue resistance are evident in the range of materials currently used in many blades. A preliminary evaluation of knockdowns for selected structural details is also presented. The high frequency database provides a significant set of data for various loading conditions in the longitudinal and transverse directions of unidirectional composites out to 10{sup 8} cycles. The results are expressed in stress and strain based Goodman Diagrams suitable for design. A discussion is provided to guide the user of the database in its application to blade design.

  1. Time-dependent deformation of composite restorative materials in compression.

    PubMed

    Cock, D J; Watts, D C

    1985-02-01

    The strain of six composite resins, including microfine and conventional types, has been measured in compression as a function of time. Compressive loads have been used in separate experiments to produce a wide range of applied stress in samples of clinically-appropriate size. The magnitude of visco-elastic response generally decreases with increasing % of filler in the composite. Additionally, the very substantial linear strain, up to 20%, observed in some microfine composites suggests the visco-elastic deformation of both organic filler, as well as resin matrix, at high stress levels. Caution is therefore indicated with regard to the clinical use of microfine restorative materials in high-stress-bearing situations. PMID:3156163

  2. Degradation of experimental composite materials and in vitro wear simulation

    NASA Astrophysics Data System (ADS)

    Givan, Daniel Allen

    2001-12-01

    The material, mechanical, and clinical aspects of surface degradation of resin composite dental restorative materials by in vitro wear simulation continues to be an area of active research. To investigate wear mechanisms, a series of experimental resin composites with variable and controlled filler particle shape and loading were studied by in vitro wear simulation. The current investigation utilized a simulation that isolated the wear environment, entrapped high and low modulus debris, and evaluated the process including machine and fluid flow dynamics. The degradation was significantly affected by filler particle shape and less by particle loading. The spherical particle composites demonstrated wear loss profiles suggesting an optimized filler loading may exist. This was also demonstrated by the trends in the mechanical properties. Very little difference in magnitude was noted for the wear of irregular particle composites as a function of particulate size; and as a group they were more wear resistant than spherical particle composites. This was the result of different mechanisms of wear that were correlated with the three-dimensional particle shape. The abrasive effects of the aggregate particles and the polymeric stabilization of the irregular shape versus the destabilization and "plucking" of the spherical particles resulted in an unprotected matrix that accounted for significantly greater wear of spherical composite. A model and analysis was developed to explain the events associated with the progressive material wear loss. The initial phase was explained by fatigue-assisted microcracking and loss of material segments in a zone of high stress immediately beneath a point of high stress contact. The early phase was characterized by the development of a small facet primarily by fatigue-assisted microcracking. Although the translation effects were minimal, some three-body and initial two-body wear events were also present. In the late phases, the abrasive effects of the debris aggregate predominated the wear process. The non-linear rate of wear loss was accelerated as the facet deepened. Physical effects, such as thermal fatigue, and chemical effects were less important but contributed to the degradation process. This study provides new insight into the role(s) of high modulus third body debris in the wear of dental composites.

  3. Explorations in the application of nanotechnology to improve the mechanical properties of composite materials

    NASA Astrophysics Data System (ADS)

    Yang, Cheng

    2007-12-01

    This thesis presents the research achievements on the design, preparation, characterization, and analysis of a series of composite materials. By studying the interface interaction of the composite materials using nanotechnology, we developed composite materials that achieve satisfactory mechanical properties in two classes of materials. Durable press (DP) natural textiles are important consumer products usually achieved by erosslinking the molecules in the textiles to achieve long-term wrinkle resistance, which, however, also leads to the simultaneous significant drop of mechanical properties. Herein, a series of polymeric nanoparticl es were investigated, the application of as little as ˜0.14 wt% addition of the nanoparticles improved the mechanical property of the DP cotton fabric by 56% in tearing resistance and 100% in abrasion resistance; the loss in recovery angle is negligible. The author also studied the enzyme-triggered DP treatments of silk fabrics, as a green process method. After the treatment of enzymes, excellent DP property was achieved with improved strain property. Injectable calcium phosphate powder containing acrylic bone cements are widely used in orthopedic surgery to fix artificial prostheses. However, the bending strength is still unsatisfactory. The author modified the surface of the strontium (Sr) containing hydroxyapatite (HA) filler powders with acrylolpamidronate in order to improve the overall mechanical performance of the bone cement composites. By adding 0.25 wt% of acrylolpamidronate to the Sr-HA nanopowders, more than 19% of the bending strength and more than 23% compression strength of the Sr-HA bone cement were improved. Biological evaluations revealed that these bone cement composites were biocompatible and bioactive in cell culture. The results obtained in this thesis work show an effective method to significantly enhance the mechanical properties of composite materials. Different from other available methods, by developing a new series of chemical compounds and nanoparticles, we successfully bound them to the surface or to the constitutional components of the materials through covalent bond. The treatment can enhance and modulate the interface-bonding of the filler materials and enhances the mechanical property of the surface through grafting a thin nano-layer. Since only surface reaction is involved, very small amount of the new material is needed, and the treatment can be readily integrated to the existing processes. The work is instructive in modifying available composite materials to acquire ultra-high mechanical performance.

  4. Novel composite piezoelectric material for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Janusas, Giedrius; Guobiene, Asta; Palevicius, Arvydas; Prosycevas, Igoris; Ponelyte, Sigita; Baltrusaitis, Valentinas; Sakalys, Rokas

    2015-04-01

    Past few decades were concentrated on researches related to effective energy harvesting applied in modern technologies, MEMS or MOEMS systems. There are many methods for harvesting energy as, for example, usage of electromagnetic devices, but most dramatic changes were noticed in the usage of piezoelectric materials in small scale devices. Major limitation faced was too small generated power by piezoelectric materials or high resonant frequencies of such smallscale harvesters. In this research, novel composite piezoelectric material was created by mixing PZT powder with 20% solution of polyvinyl butyral in benzyl alcohol. Obtained paste was screen printed on copper foil using 325 mesh stainless steel screen and dried for 30 min at 100 °C. Polyvinyl butyral ensures good adhesion and flexibility of a new material at the conditions that requires strong binding. Five types of a composite piezoelectric material with different concentrations of PZT (40%, 50%, 60%, 70% and 80 %) were produced. As the results showed, these harvesters were able to transform mechanical strain energy into electric potential and, v.v. In experimental setup, electromagnetic shaker was used to excite energy harvester that is fixed in the custom-built clamp, while generated electric potential were registered with USB oscilloscope PICO 3424. The designed devices generate up to 80 ?V at 50 Hz excitation. This property can be applied to power microsystem devices or to use them in portable electronics and wireless sensors. However, the main advantage of the created composite piezoelectric material is possibility to apply it on any uniform or nonuniform vibrating surface and to transform low frequency vibrations into electricity.

  5. Material properties and fractography of an indirect dental resin composite

    PubMed Central

    Quinn, Janet B.; Quinn, George D.

    2011-01-01

    Objectives Determination of material and fractographic properties of a dental indirect resin composite material. Methods A resin composite (Paradigm, 3M-ESPE, MN) was characterized by strength, static elastic modulus, Knoop hardness, fracture toughness and edge toughness. Fractographic analyses of the broken bar surfaces was accomplished with a combination of optical and SEM techniques, and included determination of the type and size of the failure origins, and fracture mirror and branching constants. Results The flexure test mean strength ± standard deviation was 145 MPA ± 17 MPa, and edge toughness, Te, was 172 N/mm ±12 N/mm. Knoop hardness was load dependent, with a plateau at 0.99 GPa ± .02 GPa. Mirrors in the bar specimens were measured with difficulty, resulting in a mirror constant of approximately 2.6 MPa·m1/2. Fracture in the bar specimens initiated at equiaxed material flaws that had different filler concentrations that sometimes were accompanied by partial microcracks. Using the measured flaw sizes, which ranged from 35 µm to 100 µm in size, and estimates of the stress intensity shape factors, fracture toughness was estimated to be 1.1 MPa·m1/2 ± 0.2 MPa·m1/2. Significance Coupling the flexure tests with fractographic examination enabled identification of the intrinsic strength limiting flaws. The same techniques could be useful in determining if clinical restorations of similar materials fail from the same causes. The existence of a strong load-dependence of the Knoop hardness of the resin composite is not generally mentioned in the literature, and is important for material comparisons and wear evaluation studies. Finally, the edge toughness test was found promising as a quantitative measure of resistance to edge chipping, an important failure mode in this class of materials. PMID:20304478

  6. Carbonization of wood at 400°C for composite materials

    NASA Astrophysics Data System (ADS)

    Randrianarisoa, Bernard Laurent

    The carbonization process for large pieces of wood was investigated to produce a solid carbonized wood skeleton precursor that retains the cellular structure of the wood without the formation of cracks and with reduced longitudinal deformation. Two carbonization schedules were designed for the conversion of sugar maple (Acer saccharum) and southern pine ( Pinus spp) into amorphous carbon at a heat treatment temperature of 400°C. Samples from commercial lumber were carbonized to produce the materials. Each schedule was designed meticulously through DTA-TGA for each wood species. The materials were characterized by their average yields, dimensional changes, density, porosity, SEM and mechanical testing. Also, the materials were used as solid carbon skeletons for making resin-infused carbon composites. Structural epoxy resin was infused into the carbon material template and cured at a maximum temperature of 125°C. The depth of the resin infusion was assessed by SEM examination and the retention was analyzed by total weight gain. The strength and the stiffness of the composite materials were evaluated through mechanical testing. It was demonstrated that southern pine and sugar maple should require different heat treatment schedules for carbonization. The schedules were able to reduce the longitudinal deformation and to keep the final products free of cracks. The yield averaged around 28% for both southern pine and sugar maple. Carbonized southern pine exhibited lower density and higher porosity than carbonized sugar maple. The resin treatment increased specific gravity of carbonized materials by 9.6% and 11.6% for maple and southern pine respectively. The resin infusion improved the average MOR values by 140% and 275%. MOE of the composites was similar to that of pure epoxy.

  7. Composite materials for Ericsson-like magnetic refrigeration cycle

    NASA Astrophysics Data System (ADS)

    Sma?Ìli, A.; Chahine, R.

    1997-01-01

    The ideal magnetic Ericsson refrigeration cycle should have a constant induced magnetic entropy change as a function of temperature over the whole refrigeration range. To realize this condition using composite materials, a numerical method has been developed to determine the optimum proportions of the component materials in such refrigerants. This paper investigates the effects of increasing the number (n) of the components on the constancy of the magnetic entropy change of the composite (?Scom), and suggests some new composite refrigerants. For this purpose, the Gd1-x-Dyx (with x=0, 0.12, 0.28, 0.49, and 0.70) alloys, have been used. The values of ?S have been calculated both from mean-field theory as well as from experimental magnetization curves of these alloys, in the 0.1-7 T magnetic field range and the 200-300 K temperature range. Two sets of composite materials have then been proposed as refrigerants, operating, respectively, over the temperature range 240-290 K and 210-290 K. The ?S data of the individual Gd-Dy alloys were then used to calculate the optimum mass ratio of the composites. The resultant ?Scom is practically constant in the required temperature range and amounts to 8.0 and 7.3 J/kg K for the two respective sets. The results show that a subsequent increase of n can improve the constancy of the value of ?Scom, and, hence, the corresponding refrigerant should operate more efficiently. Thus, it is found that the appropriate values of n are 3 and 4, respectively, for the first and the second set.

  8. Composite materials for Ericsson-like magnetic refrigeration cycle

    SciTech Connect

    Smaieli, A.; Chahine, R. [Institut de Recherche sur l`Hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Quebec, Canada, G9A 5H7 (CANADA)] [Institut de Recherche sur l`Hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Quebec, Canada, G9A 5H7 (CANADA)

    1997-01-01

    The ideal magnetic Ericsson refrigeration cycle should have a constant induced magnetic entropy change as a function of temperature over the whole refrigeration range. To realize this condition using composite materials, a numerical method has been developed to determine the optimum proportions of the component materials in such refrigerants. This paper investigates the effects of increasing the number (n) of the components on the constancy of the magnetic entropy change of the composite ({Delta}S{sub com}), and suggests some new composite refrigerants. For this purpose, the Gd{sub 1{minus}x}{endash}Dy{sub x} (with x=0, 0.12, 0.28, 0.49, and 0.70) alloys, have been used. The values of {Delta}S have been calculated both from mean-field theory as well as from experimental magnetization curves of these alloys, in the 0.1{endash}7 T magnetic field range and the 200{endash}300 K temperature range. Two sets of composite materials have then been proposed as refrigerants, operating, respectively, over the temperature range 240{endash}290 K and 210{endash}290 K. The {Delta}S data of the individual Gd{endash}Dy alloys were then used to calculate the optimum mass ratio of the composites. The resultant {Delta}S{sub com} is practically constant in the required temperature range and amounts to 8.0 and 7.3 J/kgK for the two respective sets. The results show that a subsequent increase of n can improve the constancy of the value of {Delta}S{sub com}, and, hence, the corresponding refrigerant should operate more efficiently. Thus, it is found that the appropriate values of n are 3 and 4, respectively, for the first and the second set. {copyright} {ital 1997 American Institute of Physics.}

  9. Novel synthesis strategies for natural polymer and composite biomaterials as potential scaffolds for tissue engineering

    PubMed Central

    Ko, Hsu-Feng; Sfeir, Charles; Kumta, Prashant N.

    2010-01-01

    Recent developments in tissue engineering approaches frequently revolve around the use of three-dimensional scaffolds to function as the template for cellular activities to repair, rebuild and regenerate damaged or lost tissues. While there are several biomaterials to select as three-dimensional scaffolds, it is generally agreed that a biomaterial to be used in tissue engineering needs to possess certain material characteristics such as biocompatibility, suitable surface chemistry, interconnected porosity, desired mechanical properties and biodegradability. The use of naturally derived polymers as three-dimensional scaffolds has been gaining widespread attention owing to their favourable attributes of biocompatibility, low cost and ease of processing. This paper discusses the synthesis of various polysaccharide-based, naturally derived polymers, and the potential of using these biomaterials to serve as tissue engineering three-dimensional scaffolds is also evaluated. In this study, naturally derived polymers, specifically cellulose, chitosan, alginate and agarose, and their composites, are examined. Single-component scaffolds of plain cellulose, plain chitosan and plain alginate as well as composite scaffolds of cellulose–alginate, cellulose–agarose, cellulose–chitosan, chitosan–alginate and chitosan–agarose are synthesized, and their suitability as tissue engineering scaffolds is assessed. It is shown that naturally derived polymers in the form of hydrogels can be synthesized, and the lyophilization technique is used to synthesize various composites comprising these natural polymers. The composite scaffolds appear to be sponge-like after lyophilization. Scanning electron microscopy is used to demonstrate the formation of an interconnected porous network within the polymeric scaffold following lyophilization. It is also established that HeLa cells attach and proliferate well on scaffolds of cellulose, chitosan or alginate. The synthesis protocols reported in this study can therefore be used to manufacture naturally derived polymer-based scaffolds as potential biomaterials for various tissue engineering applications. PMID:20308112

  10. Ultrasonic and radiographic evaluation of advanced aerospace materials: Ceramic composites

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.

    1990-01-01

    Two conventional nondestructive evaluation techniques were used to evaluate advanced ceramic composite materials. It was shown that neither ultrasonic C-scan nor radiographic imaging can individually provide sufficient data for an accurate nondestructive evaluation. Both ultrasonic C-scan and conventional radiographic imaging are required for preliminary evaluation of these complex systems. The material variations that were identified by these two techniques are porosity, delaminations, bond quality between laminae, fiber alignment, fiber registration, fiber parallelism, and processing density flaws. The degree of bonding between fiber and matrix cannot be determined by either of these methods. An alternative ultrasonic technique, angular power spectrum scanning (APSS) is recommended for quantification of this interfacial bond.

  11. Effective material properties of thermoelectric composites with elliptical fibers

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Ze

    2015-06-01

    In the present work, the effective material properties of thermoelectric composites with elliptical fibers are studied. Explicit solutions are derived by the conformal mapping function and Mori-Tanaka method. Numerical simulations are performed to present the behaviors of normalized effective material constants. From the results, it can be observed that both the effective electric and thermal conductivities can be reduced by increasing the filling ratio and a/ b. Such influences can also be found for the effective thermoelectric figure of merit. But they are different from those on the effective Seebeck and Peltier coefficients.

  12. Compositional analysis of water-soluble materials in switchgrass.

    PubMed

    Chen, Shou-Feng; Mowery, Richard A; Sevcik, Richard S; Scarlata, Christopher J; Chambliss, C Kevin

    2010-03-24

    Any valuation of a potential feedstock for bioprocessing is inherently dependent upon detailed knowledge of its chemical composition. Accepted analytical procedures for compositional analysis of biomass water-soluble extracts currently enable near-quantitative mass closure on a dry weight basis. Techniques developed in conjunction with a previous analytical assessment of corn stover have been applied to assess the composition of water-soluble materials in four representative switchgrass samples. To date, analytical characterization of water-soluble material in switchgrass has resulted in >78% mass closures for all four switchgrass samples, three of which have a mass closure of >85%. Over 30 previously unknown constituents in aqueous extracts of switchgrass were identified and quantified using a variety of chromatographic techniques. Carbohydrates (primarily sucrose, glucose, and fructose) were found to be the predominant water-soluble components of switchgrass, accounting for 18-27% of the dry weight of extractives. Total glycans (monomeric and oligomeric sugars) contributed 25-32% to the dry weight of extractives. Additional constituents contributing to the mass balance for extractives included various alditols (2-3%), organic acids (10-13%), inorganic ions (11-13%), and a distribution of oligomers presumed to represent a diverse mixture of lignin-carbohydrate complexes (30-35%). Switchgrass results are compared with previous analyses of corn stover extracts and presented in the context of their potential impact on biomass processing, feedstock storage, and future analyses of feedstock composition. PMID:20170111

  13. Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials

    NASA Astrophysics Data System (ADS)

    Muñoz, Raúl; Delgado, Sofía; González, Carlos; López-Romano, Bernardo; Wang, De-Yi; LLorca, Javier

    2014-02-01

    Carbon fiber-reinforced polymers, used in primary structures for aircraft due to an excellent strength-to-weight ratio when compared with conventional aluminium alloy counterparts, may nowadays be considered as mature structural materials. Their use has been extended in recent decades, with several aircraft manufacturers delivering fuselages entirely manufactured with carbon composites and using advanced processing technologies. However, one of the main drawbacks of using such composites entails their poor electrical conductivity when compared with aluminium alloy competitors that leads to lightning strikes being considered a significant threat during the service life of the aircraft. Traditionally, this problem was overcome with the use of a protective copper/bronze mesh that added additional weight and reduced the effectiveness of use of the material. Moreover, this traditional sizing method is based on vast experimental campaigns carried out by subjecting composite panels to simulated lightning strike events. While this method has proven its validity, and is necessary for certification of the structure, it may be optimized with the aid provided by physically based numerical models. This paper presents a model based on the finite element method that includes the sources of damage observed in a lightning strike, such as thermal damage caused by Joule overheating and electromagnetic/acoustic pressures induced by the arc around the attachment points. The results of the model are compared with lightning strike experiments carried out in a carbon woven composite.

  14. Composite material from recycled polyester for recyclable automobile structures

    SciTech Connect

    Lertola, J.G. [DuPont Company, Newark, DE (United States)

    1995-12-31

    DuPont has developed a compression-moldable composite made from the thermoplastic polyester PET and long glass fibers. This material, XTC{trademark}, is part of the class of materials known as GMT`s, or glass-mat thermoplastics. The PET content in XTC{trademark} allows the use of a wide variety of recycled material that might otherwise end up in landfills and incinerators. DuPont has succeeded in using 100% post-consumer polyester, from bottles, film, or fibers, in the composite. Since processing involves heating the material to the melt in air, the main technical issues are hydrolysis and oxidative degradation. Impurities in the recycled material must be carefully monitored, as they often increase the extent of degradation. The product itself, used to mold shaped structures and body panels for automobiles, may be recycled after its useful life. Depending on the needed purity level, processes ranging from injection molding to methanolysis can turn ground XTC{trademark} parts back into new, useful products.

  15. The behavior of sandwich structures of isotropic and composite materials

    SciTech Connect

    Vinson, J. (Univ. of Delaware, Newark, DE (United States). Mechanical Engineering Dept.)

    1999-01-01

    The Behavior of Sandwich Structures of Isotropic and Composite Materials provides a unique presentation of mathematics, descriptions and analysis of techniques in the growing field of sandwich structures. Everything is covered, from a background of sandwich structures, to thermoelastic problems of sandwich structures, sandwich shell theory and much more. This test is ideal for the engineer-in-training, as well as the practical engineer who desires a comprehensive understanding of sandwich structures technology.

  16. The measurement of porosity in composite materials using infrared thermography

    NASA Astrophysics Data System (ADS)

    Connolly, Mark P.

    1992-12-01

    The possibility of using infrared tomography for inspecting fiber-reinforced polymer matrix composite materials for the presence and extent of porosity is investigated experimentally. The technique involves heating one face of the sample with a laser and observing the temperature rise on the other face as the heat diffuses through the sample. Experimental results obtained for carbon/epoxy samples with a range of known porosities are presented. Good correlation between the diffusivity and porosity is obtained for the samples tested.

  17. Carbon-Carbon Composite Materials for Friction Purposes

    Microsoft Academic Search

    Igor V. Gurin; I. M. Neklyudov; S. G. Fursov

    2001-01-01

    Results of studies presented are aimed at developing brake disks for aeroplanes, automobiles, and other spheres of application using thermal-gradient gas-phase methods for compaction. An equation is suggested making it possible to calculate the maximum final density of carbon-carbon composite materials prepared by thermal-gradient gas-phase methods, in relation to the specific content and density of the filler. Results are given

  18. Phase interaction in composite materials Zr-Mo, W

    Microsoft Academic Search

    D. M. Karpinos; L. R. Vishnyakov; V. P. Moroz; T. N. Bondarenko; V. P. Dzeganovskii

    1987-01-01

    Composite materials based on the thermodynamically unstable systems Zr-Mo and Zr-W have satisfactory kinetic stability of the structure up to 1373°K. At higher temperatures there occurs intense interaction between fibers and matrix entailingthe formation of solid solutions and intermetallic phases. The course of the diffusion processes in the investigated CM is determined by the history of their components, and this

  19. Composite slip table of dissimilar materials for damping longitudinal modes

    DOEpatents

    Gregory, Danny L. (Albuquerque, NM); Priddy, Tommy G. (Albuquerque, NM); Smallwood, David O. (Albuquerque, NM); Woodall, Tommy D. (Albuquerque, NM)

    1991-01-01

    A vibration slip table for use in a vibration testing apparatus. The table s comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes.

  20. Nanocrystal-Based Polymer Composites as Novel Functional Materials

    Microsoft Academic Search

    M. Striccoli; M. L. Curri; R. Comparelli

    \\u000a This chapter provides an overall picture of nanocrystal-polymer based composites and describes the key properties of these\\u000a original functional materials, particularly suited for advanced applications in photonic, optoelectronic as well as in sensing.\\u000a Here, we aim at pointing out the relevance of the incorporation of inorganic colloidal nanocrystals with size-dependent properties\\u000a in highly processable polymers. Due to the countless different

  1. Non-destructive evaluation of composite materials using ultrasound

    NASA Technical Reports Server (NTRS)

    Miller, J. G.

    1984-01-01

    Investigation of the nondestructive evaluation of advanced composite-laminates is summarized. Indices derived from the measurement of fundamental acoustic parameters are used in order to quantitatively estimate the local material properties of the laminate. The following sections describe ongoing studies of phase insensitive attenuation measurements, and discuss several phenomena which influences the previously reported technique of polar backscatter. A simple and effective programmable gate circuit designed for use in estimating attenuation from backscatter is described.

  2. Color stability of highly filled composite resin materials for facings

    Microsoft Academic Search

    T Stober; H Gilde; P Lenz

    2001-01-01

    Objectives: The aim of the investigation was to examine the color stability of seven resin-based facing composites with a high content of inorganic filling material (Colombus, Artglass, Sinfony, Targis, Zeta LC, Zeta HC, BelleGlass HP\\/dentine, BelleGlass HP\\/enamel).Methods: Changes in color of test samples were determined after UV irradiation in a fast-action UV instrument, Sunset CPS+, and after storage in a

  3. Protecting spacecraft against orbital debris impact damage using composite materials

    Microsoft Academic Search

    W. P Schonberg

    2000-01-01

    All earth-orbiting spacecrafts are susceptible to impacts by meteoroids and pieces of orbital debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic spacecraft failure. With the advent of many new high-strength composite materials and their proliferation in aircraft applications, it is necessary to evaluate their potential for use in

  4. Mechanical response of a mine composite material to extreme heat

    Microsoft Academic Search

    L. Orejarena; M. Fall

    2008-01-01

    The use of cemented paste backfills (CPB, a mine composite tailings material) in underground mining is currently increasing\\u000a in importance globally. However, despite the tremendous progress made in understanding the factors affecting the performance\\u000a of CPB, little attention has been devoted to the impact of high temperatures on its mechanical properties. This article presents\\u000a the results of experimental investigations into

  5. On the Mechanical Behavior of Advanced Composite Material Structures

    Microsoft Academic Search

    Jack Vinson

    2009-01-01

    \\u000a During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be\\u000a supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of\\u000a composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding

  6. The Abundance and Isotopic Composition of Hg in Extraterrestrial Materials

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.

    2004-01-01

    During the past three year grant period we made excellent progress in our study of the abundances and isotopic compositions of Hg and other volatile trace elements in extraterrestrial materials. As part of my startup package I received funds to construct a state-of-the-art experimental facility to study gas-solid reaction kinetics. Much of our effort was spent developing the methodology to measure the abundance and isotopic composition of Hg at ultratrace levels in solid materials. In our first study, the abundance and isotopic composition of Hg was determined in bulk samples of the Murchison (CM) and Allende (CV) carbonaceous chondrites. We have continued our study of mercury in primitive meteorites and expanded the suite of meteorites to include other members of the CM and CV chondrite group as well as CI and CO chondrites. Samples of the CI chondrite Orgueil, the CM chondrites Murray, Nogoya, and Cold Bokkeveld, the CO chondrites Kainsaz, Omans, and Isna, and the CV chondrites Vigarano, Mokoia, and Grosnaja were tested. We have developed a thermal analysis ICP-MS technique and applied it to the study of a suite of thermally labile elements (Zn, As, Se, Cd, In, Sn, Sb, Te, Hg, Au, Tl, Pb, and Bi) in geologic materials as well.

  7. Strain Gage Selection Criteria for Textile Composite Materials

    NASA Technical Reports Server (NTRS)

    Masters, John E.

    1996-01-01

    This report will provide a review of efforts to establish a set of strain gage selection guidelines for textile reinforced composite materials. A variety of strain gages were evaluated in the study to determine the sensitivity of strain measurements to the size of the strain gage. The strain gages were chosen to provide a range of gage lengths and widths. The gage aspect ratio (the length-to-width ratio) was also varied. The gages were tested on a diverse collection of textile composite laminates. Test specimens featured eleven different textile architectures: four 2-D triaxial braids, six 3-D weaves, and one stitched uniweave architecture. All specimens were loaded in uniaxial tension. The materials' moduli were measured in both the longitudinal (parallel to the O deg. yarns) and the transverse (perpendicular to the O deg. yarns) directions. The results of these measurements were analyzed to establish performance levels for extensometers and strain gages on textile composite materials. Conclusions are expressed in a summary that discusses instrumentation practices and defines strain gage selection criteria.

  8. Autonomic composite hydrogels by reactive printing: materials and oscillatory response.

    PubMed

    Kramb, R C; Buskohl, P R; Slone, C; Smith, M L; Vaia, R A

    2014-03-01

    Autonomic materials are those that automatically respond to a change in environmental conditions, such as temperature or chemical composition. While such materials hold incredible potential for a wide range of uses, their implementation is limited by the small number of fully-developed material systems. To broaden the number of available systems, we have developed a post-functionalization technique where a reactive Ru catalyst ink is printed onto a non-responsive polymer substrate. Using a succinimide-amine coupling reaction, patterns are printed onto co-polymer or biomacromolecular films containing primary amine functionality, such as polyacrylamide (PAAm) or poly-N-isopropyl acrylamide (PNIPAAm) copolymerized with poly-N-(3-Aminopropyl)methacrylamide (PAPMAAm). When the films are placed in the Belousov-Zhabotinsky (BZ) solution medium, the reaction takes place only inside the printed nodes. In comparison to alternative BZ systems, where Ru-containing monomers are copolymerized with base monomers, reactive printing provides facile tuning of a range of hydrogel compositions, as well as enabling the formation of mechanically robust composite monoliths. The autonomic response of the printed nodes is similar for all matrices in the BZ solution concentrations examined, where the period of oscillation decreases in response to increasing sodium bromate or nitric acid concentration. A temperature increase reduces the period of oscillations and temperature gradients are shown to function as pace-makers, dictating the direction of the autonomic response (chemical waves). PMID:24651297

  9. Facesheet Delamination of Composite Sandwich Materials at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Odegard, Gregory M.; Herring, Helen M.

    2003-01-01

    The next generation of space transportation vehicles will require advances in lightweight structural materials and related design concepts to meet the increased demands on performance. One potential source for significant structural weight reduction is the replacement of traditional metallic cryogenic fuel tanks with new designs for polymeric matrix composite tanks. These new tank designs may take the form of thin-walled sandwich constructed with lightweight core and composite facesheets. Life-time durability requirements imply the materials must safely carry pressure loads, external structural loads, resist leakage and operate over an extremely wide temperature range. Aside from catastrophic events like tank wall penetration, one of the most likely scenarios for failure of a tank wall of sandwich construction is the permeation of cryogenic fluid into the sandwich core and the subsequent delamination of the sandwich facesheet due to the build-up of excessive internal pressure. The research presented in this paper was undertaken to help understand this specific problem of core to facesheet delamination in cryogenic environments and relate this data to basic mechanical properties. The experimental results presented herein provide data on the strain energy release rate (toughness) of the interface between the facesheet and the core of a composite sandwich subjected to simulated internal pressure. A unique test apparatus and associated test methods are described and the results are presented to highlight the effects of cryogenic temperature on the measured material properties.

  10. Ultrasonic nondestructive testing of composite materials using disturbed coincidence conditions

    NASA Astrophysics Data System (ADS)

    Bause, F.; Olfert, S.; Schröder, A.; Rautenberg, J.; Henning, B.; Moritzer, E.

    2012-05-01

    In this contribution we present a new method detecting changes in the composite material's acoustic behavior by analyzing disturbed coincidence conditions on plate-like test samples. The coincidence condition for an undamaged GFRP test sample has been experimentally identified using Schlieren measurements. Disturbances of this condition follow from a disturbed acoustic behavior of the test sample which is an indicator for local damages in the region inspected. An experimental probe has been realized consisting of two piezoceramic elements adhered to the nonparallel sides of an isosceles trapezoidal body made of silicone. The base angles of the trapezoidal body have been chosen such that the incident wave meets pre-measured condition of coincidence. The receiving element receives the geometric reflection of the acoustic wave scattered at the test sample's surface which corresponds to the non-coupled part of the incident wave as send by the sending element. Analyzing the transfer function or impulse response of the electro-acoustic system (transmitter, scattering at test sample, receiver), it is possible to detect local disturbances with respect to Cramer's coincidence rule. Thus, it is possible to realize a very simple probe for local ultrasonic nondestructive testing of composite materials (as well as non-composite material) which can be integrated in a small practical device and is good for small size inspection areas.

  11. Material Issues in Space Shuttle Composite Overwrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Sutter, James K.; Jensen, Brian J.; Gates, Thomas S.; Morgan, Roger J.; Thesken, John C.; Phoenix, S. Leigh

    2006-01-01

    Composite Overwrapped Pressure Vessels (COPV) store gases used in four subsystems for NASA's Space Shuttle Fleet. While there are 24 COPV on each Orbiter ranging in size from 19-40", stress rupture failure of a pressurized Orbiter COPV on the ground or in flight is a catastrophic hazard and would likely lead to significant damage/loss of vehicle and/or life and is categorized as a Crit 1 failure. These vessels were manufactured during the late 1970's and into the early 1980's using Titanium liners, Kevlar 49 fiber, epoxy matrix resin, and polyurethane coating. The COPVs are pressurized periodically to 3-5ksi and therefore experience significant strain in the composite overwrap. Similar composite vessels were developed in a variety of DOE Programs (primarily at Lawrence Livermore National Laboratories or LLNL), as well as for NASA Space Shuttle Fleet Leader COPV program. The NASA Engineering Safety Center (NESC) formed an Independent Technical Assessment (ITA) team whose primary focus was to investigate whether or not enough composite life remained in the Shuttle COPV in order to provide a strategic rationale for continued COPV use aboard the Space Shuttle Fleet with the existing 25-year-old vessels. Several material science issues were examined and will be discussed in this presentation including morphological changes to Kevlar 49 fiber under stress, manufacturing changes in Kevlar 49 and their effect on morphology and tensile strength, epoxy resin strain, composite creep, degradation of polyurethane coatings, and Titanium yield characteristics.

  12. A multiphase approach for modelling the shock response of composite materials

    NASA Astrophysics Data System (ADS)

    Key, C. T.; Schumacher, S. C.; Ruggirello, K. P.; Alexander, C. S.

    2014-05-01

    The shock response of unidirectional fiber reinforced composite materials is inherently anisotropic due to their microstructural geometric configuration. Unlike typical elastic-plastic materials, composite materials form the observed two-wave structure under longitudinal shocks due to a precursor wave travelling through the fibers ahead of a bulk wave in the resin constituent. The nature of this response presents a problem in traditional hydrocode frameworks where each cell or material point tracks only a single velocity field. This paper outlines an adaptation of the Baer and Nunziato multi-phase model in CTH where a mixture rule is used to determine the velocity field of each constituent (fiber and matrix) of the composite material. The model modifies the momentum exchange term to represent the frictional drag forces between the fiber and matrix constituents, while assuming no mass or energy exchange. The momentum drag model is dependent not only upon the pressure difference between the constituents but also the directional dependence of the shock response. Finally, the model is implemented and the sensitivity of the solution to the interaction parameters demonstrated.

  13. Ductile and brittle material removal mechanisms in natural nacre—A model for novel implant materials

    Microsoft Academic Search

    Berend Denkena; Jens Koehler; Analía Moral

    2010-01-01

    Nacre is a composite material found in the inner layer of sea shells. It consists of soft organic and hard inorganic components arranged in a complex hierarchical structure. Due to this arrangement, nacre exhibits outstanding mechanical properties (elastic modulus: 64.70±3.50GPa, hardness: 4.41±0.45GPa, density: 2.6g\\/cm3). Therefore, nacreous implant materials have a high potential in many fields. In medical science, these materials

  14. Size-controlled hydroxyapatite nanoparticles as self-organized organic-inorganic composite materials.

    PubMed

    Rusu, Viorel Marin; Ng, Chuen-How; Wilke, Max; Tiersch, Brigitte; Fratzl, Peter; Peter, Martin G

    2005-09-01

    This paper presents some results concerning the size-controlled hydroxyapatite nanoparticles obtained in aqueous media in a biopolymer matrix from soluble precursors salts. Taking the inspiration from nature, where composite materials made of a polymer matrix and inorganic fillers are often found, e.g. bone, shell of crustaceans, shell of eggs, etc., the feasibility on making composite materials containing chitosan and nanosized hydroxyapatite was investigated. A stepwise co-precipitation approach was used to obtain different types of composites by means of different ratio between components. The synthesis of hydroxyapatite was carried out in the chitosan matrix from calcium chloride and sodium dihydrogenphosphate in alkaline solutions at moderate pH of 10-11 for 24 h. Our research is focused on studying and understanding the structure of this class of composites, aiming at the development of novel materials, controlled at the nanolevel scale. The X-ray diffraction technique was employed in order to study the kinetic of hydroxyapatite formation in the chitosan matrix as well as to determine the HAp crystallite sizes in the composite samples. The hydroxyapatite synthesized using this route was found to be nano-sized (15-50 nm). Moreover, applying an original approach to analyze the (002) XRD diffraction peak profile of hydroxyapatite by using a sum of two Gauss functions, the bimodal distribution of nanosized hydroxyapatite within the chitosan matrix was revealed. Two types of size distribution domains such as cluster-like (between 200 and 400 nm), which are the habitat of ''small'' hydroxyapatite nanocrystallites and scattered-like, which are the habitat of ''large'' hydroxyapatite nanocrystallites was probed by TEM and CSLM. The structural features of composites suggest that self-assembly processes might be involved. The composites contain nanosized hydroxyapatite with structural features close to those of biological apatites that make them attractive for bone tissue engineering applications. PMID:15814140

  15. Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases

    USGS Publications Warehouse

    Román Colón, Yomayra A.; Ruppert, Leslie F.

    2015-01-01

    The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

  16. Composite material pedestrian bridge for the Port of Bilbao

    NASA Astrophysics Data System (ADS)

    Gorrochategui, I.; Manteca, C.; Yedra, A.; Miguel, R.; del Valle, F. J.

    2012-09-01

    Composite materials in comparison to traditional ones, steel and concrete, present advantages in civil works construction: lower weight, higher corrosion resistance (especially in the marine environment), and ease of installation. On the other hand, fabrication costs are generally higher. This is the reason why this technology is not widely used. This work illustrates the process followed for the design, fabrication and installation of a composite material pedestrian bridge in the Port of Bilbao (Northern Spain). In order to reduce the price of the bridge, the use of low cost materials was considered, therefore polyester resin was selected as the polymeric matrix, and glass fibres as reinforcement. Two material choices were studied. Currently in the market there is high availability of carbon nanoparticles: carbon nanotubes (CNT) and carbon nanofibres (CNF), so it was decided to add this kind of nanoparticles to the reference material with the objective of improving its mechanical properties. The main challenge was to transfer the CNT and CNF excellent properties to the polymeric matrix. This requires dispersing the nanoreinforcements as individual particles in the polymeric matrix to avoid agglomerates. For this reason, an advanced high shear forces dispersion technique (called "three roll mills") was studied and implemented. Also surface functionalization of the nanoreinforcements by chemical treatment was carried out. Herein, a comparison is performed between both materials studied, the explanation of the employment of the reference material (without nanoreinforcement) as the one used in the fabrication of the pedestrian bridge is justified and, finally, the main characteristics of the final design of the structural element are described.

  17. Determination of Residual Stress in Composite Materials Using Ultrasonic Waves

    NASA Technical Reports Server (NTRS)

    Rokhlin, S. I.

    1997-01-01

    The performance of high temperature composites can be significantly affected by the presence of residual stresses. These stresses arise during cooling processes from fabrication to room temperature due to mismatch of thermal expansion coefficients between matrix and fiber materials. This effect is especially pronounced in metal matrix and intermetallic composites. It can lead to plastic deformations, matrix cracking and fiber/matrix interface debonding. In this work the feasibility of ultrasonic techniques for residual stress assessment in composites is addressed. A novel technique for absolute stress determination in orthotropic materials from angular dependencies of ultrasonic velocities is described. The technique is applicable for determination of both applied and residual stresses and does not require calibration measurements on a reference sample. The important advantage of this method is that stress is determined simultaneously with stress-dependent elastic constants and is thus decoupled from the material texture. It is demonstrated that when the principal plane stress directions coincide with acoustical axes, the angular velocity data in the plane perpendicular to the stress plane may be used to determine both stress components. When the stress is off the acoustical axes, the shear and the difference of the normal stress components may be determined from the angular dependence of group velocities in the plane of stresses. Synthetic sets of experimental data corresponding to materials with different anisotropy and stress levels are used to check the applicability of the technique. The method is also verified experimentally. A high precision ultrasonic wave transmission technique is developed to measure angular dependence of ultrasonic velocities. Examples of stress determination from experimental velocity data are given. A method is presented for determination of velocities of ultrasonic waves propagating through the composite material with residual stresses. It is based on the generalized self-consistent multiple scattering model. Calculation results for longitudinal and shear ultrasonic wave velocities propagating perpendicular to the fibers direction in SCS-6/Ti composite with and without residual stresses are presented. They show that velocity changes due to presence of stresses are of order 1%.

  18. Effective thermal conductivity of polycapillary composite materials. II. The influence of convective heat exchange in the channels on the effective thermal conductivity of polycapillary composite materials

    Microsoft Academic Search

    L. I. Tuchinskii; E. M. Veksler

    1992-01-01

    In the preceding article [1], an analytical relationship making it possible to determine the effective transverse thermal conductivity X.y of polycapillary composite materials was obtained. This relationship establishes the relationship between Xy, the volumetric concentration and thermal conductivity of the components of a polycapillary composite material, and the geometric parameters of the structure of the material. In deriving the equation,

  19. A novel montmorillonite-based composite phase change material and its applications in thermal storage building materials

    Microsoft Academic Search

    Xiaoming Fang; Zhengguo Zhang

    2006-01-01

    A novel composite phase change material (PCM) was prepared by blending an organic PCM with an organic-modified montmorillonite. The thermal characteristics of the composite PCM were close to those of the pure PCM, and 1500 times heating–cooling cycles test showed that the composite PCM had good performance stability. Compared with the pure PCM, the composite PCM exhibited higher heat transfer

  20. PneUI: Pneumatically Actuated Soft Composite Materials for Shape Changing Interfaces

    E-print Network

    Yao, Lining

    This paper presents PneUI, an enabling technology to build shape-changing interfaces through pneumatically-actuated soft composite materials. The composite materials integrate the capabilities of both input sensing and ...

  1. A Nanoscale Composite Material for Enhanced Damage Tolerance in MEMS Applications

    E-print Network

    MacDonald, Noel C.

    A Nanoscale Composite Material for Enhanced Damage Tolerance in MEMS Applications A. Paranjpye this concept at the microscale, towards obtaining fracture resistant MEMS structures. Cantilever beams of this laminar composite material, manufactured by MEMS fabrication methods are deflected to fracture

  2. Experimental identification of smart material coupling effects in composite structures

    NASA Astrophysics Data System (ADS)

    Chesne, S.; Jean-Mistral, C.; Gaudiller, L.

    2013-07-01

    Smart composite structures have an enormous potential for industrial applications, in terms of mass reduction, high material resistance and flexibility. The correct characterization of these complex structures is essential for active vibration control or structural health monitoring applications. The identification process generally calls for the determination of a generalized electromechanical coupling coefficient. As this process can in practice be difficult to implement, an original approach, presented in this paper, has been developed for the identification of the coupling effects of a smart material used in a composite curved beam. The accuracy of the proposed identification technique is tested by applying active modal control to the beam, using a reduced model based on this identification. The studied structure was as close to reality as possible, and made use of integrated transducers, low-cost sensors, clamped boundary conditions and substantial, complex excitation sources. PVDF (polyvinylidene fluoride) and MFC (macrofiber composite) transducers were integrated into the composite structure, to ensure their protection from environmental damage. The experimental identification described here was based on a curve fitting approach combined with the reduced model. It allowed a reliable, powerful modal control system to be built, controlling two modes of the structure. A linear quadratic Gaussian algorithm was used to determine the modal controller-observer gains. The selected modes were found to have an attenuation as strong as -13 dB in experiments, revealing the effectiveness of this method. In this study a generalized approach is proposed, which can be extended to most complex or composite industrial structures when they are subjected to vibration.

  3. Poly(vinylidene fluoride)/zinc oxide smart composite material

    NASA Astrophysics Data System (ADS)

    Ö?üt, Erdem; Yördem, O. Sinan; Mencelo?lu, Yusuf Z.; Papila, Melih

    2007-04-01

    This work aimed at fabrication and electromechanical characterization of a smart material system composed of electroactive polymer and ceramic materials. The idea of composite material system is on account of complementary characteristics of the polymer and ceramic for flexibility and piezoelectric activity. Our preliminary work included Polyvinylidene Fluoride (PVDF) as the flexible piezoelectric polymer, and Zinc Oxide (ZnO) as the piezoelectric ceramic brittle, but capable to respond strains without poling. Two alternative processes were investigated. The first process makes use of ZnO fibrous formation achieved by sintering PVA/zinc acetate precursor fibers via electrospinning. Highly brittle fibrous ZnO mat was dipped into a PVDF polymer solution and then pressed to form pellets. The second process employed commercial ZnO nanopowder material. The powder was mixed into a PVDF/acetone polymer solution, and the resultant paste was pressed to form pellets. The free standing composite pellets with electrodes on the top and bottom surfaces were then subjected to sinusoidal electric excitation and response was recorded using a fotonic sensor. An earlier work on electrospun PVDF fiber mats was also summarized here and the electromechanical characterization is reported.

  4. TRANSTRAIN: A program to compute strain transformations in composite materials

    NASA Technical Reports Server (NTRS)

    Ahmed, Rafiq

    1990-01-01

    Over the years, the solid rocket motor community has made increasing use of composite materials for thermal and structural applications. This is particularly true of solid rocket nozzles, which have used carbon phenolic and, increasingly, carbon-carbon materials to provide structural integrity and thermal protection at the high temperatures encountered during motor burn. To evaluate the degree of structural performance of nozzles and their materials and to verify analysis models, many subscale and full-scale tests are run. These provide engineers with valuable data needed to optimize design and to analyze nozzle hardware. Included among these data are strains, pressures, thrust, temperatures, and displacements. Recent nozzle test hardware has made increasing use of strain gauges embedded in the carbon composite material to measure internal strains. In order to evaluate strength, these data must be transformed into strains along the fiber directions. The fiber-direction stresses can then be calculated. A computer program written to help engineers correctly manipulate the strain data into a form that can be used to evaluate structural integrity of the nozzle is examined.

  5. Standard Test Methods for Constituent Content of Composite Materials

    E-print Network

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 These test methods determine the constituent content of composite materials by one of two approaches. Method I physically removes the matrix by digestion or ignition by one of seven procedures, leaving the reinforcement essentially unaffected and thus allowing calculation of reinforcement or matrix content (by weight or volume) as well as percent void volume. Method II, applicable only to laminate materials of known fiber areal weight, calculates reinforcement or matrix content (by weight or volume), and the cured ply thickness, based on the measured thickness of the laminate. Method II is not applicable to the measurement of void volume. 1.1.1 These test methods are primarily intended for two-part composite material systems. However, special provisions can be made to extend these test methods to filled material systems with more than two constituents, though not all test results can be determined in every case. 1.1.2 The procedures contained within have been designed to be particularly effective for ce...

  6. Noninteractive macroscopic reliability model for ceramic matrix composites with orthotropic material symmetry

    NASA Technical Reports Server (NTRS)

    Duffy, Stephen F.; Manderscheid, Jane M.

    1989-01-01

    A macroscopic noninteractive reliability model for ceramic matrix composites is presented. The model is multiaxial and applicable to composites that can be characterized as orthotropic. Tensorial invariant theory is used to create an integrity basis with invariants that correspond to physical mechanisms related to fracture. This integrity basis is then used to construct a failure function per unit volume (or area) of material. It is assumed that the overall strength of the composite is governed by weakest link theory. This leads to a Weibull type model similar in nature to the principle of independent action (PIA) model for isotropic monolithic ceramics. An experimental program to obtain model parameters is briefly discussed. In addition, qualitative features of the model are illustrated by presenting reliability surfaces for various model parameters.

  7. Fatigue Crack Measurement in Composite Materials by Ultrasonic Methods

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Russell, Samuel S.; Suits, Michael W.; Workman, Gary L.; Watson, Jason M.; Thom, Robert (Technical Monitor)

    2002-01-01

    The nondestructive detection of intra-ply microcracking in unlined pressure vessels fabricated from composite materials is critical to ensuring mission success. Microcracking in composite structures due to combined fatigue and cryogenic thermal loading can be very troublesome to detect in-service and when it begins to link through the thickness can cause leakage and failure of the structure. These leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping. The work presented herein develops a method and an instrument to locate and measure intraply fatigue cracking through the thickness of laminated composite material by means of correlation with ultrasonic resonance. Resonant ultrasound spectroscopy provides measurements which are, sensitive to both the microscopic and macroscopic properties of an object. Elastic moduli, acoustic attenuation, and geometry can all be probed. The approach is based on the premise of half-wavelength resonance. The method injects a broadband ultrasonic wave into the test structure using a swept frequency technique. This method provides dramatically increased energy input into the test article, as compared to conventional spike pulsed ultrasonics. This relative energy increase improves the ability to measure finer details in the materials character, such as micro-cracking and porosity. As the micro-crack density increases, more interactions occur with the higher frequency (small wavelength) components of the signal train causing the spectrum to shift toward lower frequencies. Preliminary experiments have verified a measurable effect on the resonance spectrum of the ultrasonic data to detect microcracking. Methods involving self organizing neural networks and other clustering algorithms show that the resonance ultrasound signatures from composites vary with the degree of microcracking and can be separated and identified.

  8. Influence of Material Distribution on Impact Resistance of Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Abatan, Ayu; Hu, Hurang

    1998-01-01

    Impact events occur in a wide variety of circumstances. A typical example is a bullet impacting a target made of composite material. These impact events produce time-varying loads on a structure that can result in damage. As a first step to understanding the damage resistance issue in composite laminates, an accurate prediction of the transient response during an impact event is necessary. The analysis of dynamic loadings on laminated composite plates has undergone considerable development recently. Rayleigh-Ritz energy method was used to determine the impact response of laminated plates. The impact response of composite plates using shear deformation plate theory was analyzed. In recent work a closed-form solution was obtained for a rectangular plate with four edges simply supported subjected to a center impact load using classical plate theory. The problem was further investigated and the analysis results compared of both classical plate theory and shear deformation theory, and found that classical plate theory predicts very accurate results for the range of small deformations considered. In this study, the influence of cross sectional material distribution on the comparative impact responses of hybrid metal laminates subjected to low and medium velocity impacts is investigated. A simple linear model to evaluate the magnitude of the impact load is proposed first, and it establishes a relation between the impact velocity and the impact force. Then a closed-form solution for impact problem is presented. The results were compared with the finite element analysis results. For an 11 layer-hybrid laminate, the impact response as a function of material distribution in cross-section is presented. With equal areal weight, the effect of the number of laminate layers on the impact resistance is also investigated. Finally, the significance of the presented results is discussed.

  9. VISCOELASTIC PROPERTIES OF NATURAL RUBBER COMPOSITES REINFORCED BY DEFATTED SOY FLOUR AND CARBON BLACK CO-FILLER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Filler mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce natural rubber (NR) composites and their viscoelastic properties were investigated. DSF is an abundant and renewable commodity and has a lower material cost than CB. Aqueous dispersions of DSF and CB were firs...

  10. Continuation of tailored composite structures of ordered staple thermoplastic material

    NASA Technical Reports Server (NTRS)

    Santare, Michael H.; Pipes, R. Byron

    1992-01-01

    The search for the cost effective composite structure has motivated the investigation of several approaches to develop composite structure from innovative material forms. Among the promising approaches is the conversion of a planar sheet to components of complex curvature through sheet forming or stretch forming. In both cases, the potential for material stretch in the fiber direction appears to offer a clear advantage in formability over continuous fiber systems. A framework was established which allows the simulation of the anisotropic mechanisms of deformation of long discontinuous fiber laminates wherein the matrix phase is a viscous fluid. Predictions for the effective viscosities of a hyper-anisotropic medium consisting of collimated, discontinuous fibers suspended in viscous matrix were extended to capture the characteristics of typical polymers including non-Newtonian behavior and temperature dependence. In addition, the influence of fiber misorientation was also modeled by compliance averaging to determine ensemble properties for a given orientation distribution. A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams such as those used in aircraft fuselage structures. Material heterogeneity can be induced during manufacturing processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing radial and tangential gradients in material properties. Two analysis procedures are used to solve the beam problems. The first method uses separate two-dimensional elasticity solutions for the stresses in the flange and web sections of the beam. The separate solutions are coupled by requiring that forces and displacements match section boundaries. The second method uses an approximate Rayleigh-Ritz technique to find the solutions for more complex beams. Analyses are performed for curved beams of various cross-sections loaded in pure bending and with a uniform distributed load. Preliminary results show that the geometry of the beam dictates the effect of heterogeneity on performance. The role of heterogeneity is larger in beams with a small average radius-to-depth ration, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radii. Results of the anlysis are in the form of stresses and displacements and are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  11. Composite materials comprising two jonal functions and methods for making the same

    Microsoft Academic Search

    Ali Syed Fareed; John Edward Garnier; Gerhard Hans Schiroky; Christopher Robin Kennedy; Birol Sonuparlak

    2001-01-01

    The present invention generally relates to mechanisms for preventing undesirable oxidation (i.e., oxidation protection mechanisms) in composite bodies. The oxidation protection mechanisms include getterer materials which are added to the composite body which gather or scavenge undesirable oxidants which may enter the composite body. The getterer materials may be placed into at least a portion of the composite body such

  12. Corrosion and tribological properties of basalt fiber reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Ha, Jin Cheol; Kim, Yun-Hae; Lee, Myeong-Hoon; Moon, Kyung-Man; Park, Se-Ho

    2015-03-01

    This experiment has examined the corrosion and tribological properties of basalt fiber reinforced composite materials. There were slight changes of weight after the occurring of corrosion based on time and H2SO4 concentration, but in general, the weight increased. It is assumed that this happens due to the basalt fiber precipitate. Prior to the corrosion, friction-wear behavior showed irregular patterns compared to metallic materials, and when it was compared with the behavior after the corrosion, the coefficient of friction was 2 to 3 times greater. The coefficient of friction of all test specimen ranged from 0.1 to 0.2. Such a result has proven that the basalt fiber, similar to the resin rubber, shows regular patterns regardless of time and H2SO4 concentration because of the space made between resins and reinforced materials.

  13. FLUID FLOW MODELING OF RESIN TRANSFER MOLDING FOR COMPOSITE MATERIAL WIND TURBINE BLADE STRUCTURES

    E-print Network

    FLUID FLOW MODELING OF RESIN TRANSFER MOLDING FOR COMPOSITE MATERIAL WIND TURBINE BLADE STRUCTURES.................................................................................................8 Resin Systems

  14. Engineering and characterisation of the interface in flax fibre\\/polypropylene composite materials. Part I. Development and investigation of surface treatments

    Microsoft Academic Search

    N. E Zafeiropoulos; D. R Williams; C. A Baillie; F. L Matthews

    2002-01-01

    Natural fibres have long been used as cost-cutting fillers in the plastics industry. Nowadays, they are considered to be a potential replacement of glass fibres for use in composite materials. However, although natural fibres have many advantages, the most important being their low cost and low density, they are not totally free of problems. A serious problem of natural fibres

  15. Composition of Surface Materials on the Moons of Mars

    NASA Astrophysics Data System (ADS)

    Pieters, Carle M.; Murchie, Scott; Thomas, Nicolas; Britt, Daniel

    2014-11-01

    The two small asteroid-like bodies orbiting Mars, Phobos and Deimos, are low albedo and exhibit similar visible to near-infrared spectra. Determining the origin of these moons is closely tied to determining their composition. From available spectroscopic data Phobos exhibits two distinct types of materials across its surface, and data from both Mars Express and Mars Reconnaissance Orbiter have provided additional details about the properties of these materials and their spatial relation to one another. Although no prominent diagnostic absorptions have been detected, systematic weak features are seen in some data. An extensive regolith is observed to have developed on both moons with characteristics that may be unique due to their special environment in Mars orbit. Understanding the character and evolution of the regolith of Phobos and Deimos is central to interpreting the moons' physical and optical properties. The cumulative data available for compositional analyses across the surface of Phobos and Deimos, however, remain incomplete in scope and character and ambiguous in interpretation. Consequently the composition of the moons of Mars remains uncertain.

  16. Multi scale analysis by acoustic emission of damage mechanisms in natural fibre woven fabrics/epoxy composites.

    NASA Astrophysics Data System (ADS)

    Bonnafous, C.; Touchard, F.; Chocinski-Arnault, L.

    2010-06-01

    This paper proposes to develop an experimental program to characterize the type and the development of damage in composite with complex microstructure. A multi-scale analysis by acoustic emission has been developed and applied to hemp fibre woven fabrics/epoxy composite. The experimental program consists of tensile tests performed on single yarn, neat epoxy resin and composite materials to identify their AE amplitude signatures. A statistical analysis of AE amplitude signals has been realised and correlated with microscopic observations. Results have enabled to identify three types of damage in composites and their associated AE amplitudes: matrix cracking, interfacial debonding and reinforcement damage and fracture. Tracking of these damage mechanisms in hemp/epoxy composites has been performed to show the process of damage development in natural fibre reinforced composites.

  17. NATURE MATERIALS | VOL 12 | AUGUST 2013 | www.nature.com/naturematerials 683 Greece in crisis

    E-print Network

    NATURE MATERIALS | VOL 12 | AUGUST 2013 | www.nature.com/naturematerials 683 commentary Greece igher-education research and technology in Greece weren't always in dire need of reforms and economic universities. Further cause for optimism came from the fact that, in 1981, Greece became the tenth member

  18. An investigation of a boron-aluminum-base hybrid composite material

    Microsoft Academic Search

    L. R. Vishnyakov; V. P. Moroz; L. N. Tsypina

    1988-01-01

    Composite material specimens of three types with different plans of mutual location of the steel grids and single layers of boron-aluminum were investigated (Fig. 2). The composite materials of the first two groups were obtained from blanks assembled using the plan shown in Fig. 2a and the composite material blanks of the third type were assembled according to the plan

  19. The influence of automation on the cost competitiveness of advanced composite materials

    Microsoft Academic Search

    S. Krolewski; T. Gutowski

    1989-01-01

    In many applications, advanced composites offer higher performance to weight ratios than traditional aerospace materials. Since composites parts are generally expensive, the market for these materials is limited to applications which can afford to pay a premium for higher performance. There is, however, a narrow window of opportunity within which composites can compete with traditional materials. To exploit this opportunity,

  20. Infrared Spectroscopic Identification of Chosen Dental Materials and Natural Teeth

    NASA Astrophysics Data System (ADS)

    H?dzelek, W.; Marcinkowska, A.; Domka, L.; Wachowiak, R.

    2008-08-01

    Studies using solid phase infrared spectroscopy in the range of 400 to 4000 wave numbers were conducted in order to quickly identify solid tooth fragments and differentiate them from dental materials used in the dental practice. The frequently employed dental materials were evaluated. Natural chemical structure of permanent teeth obtained from donors of various ages provided the reference material. The infrared vibrations detected in infrared transmission spectra depended on the chemical structure of examined compound. Comparable distinctive peaks in infrared spectra of natural teeth and inorganic dental materials (porcelain) were exhibited. Analogous infrared spectra of dental materials consisting of organic matrix with inorganic fillers were found. In the case of acrylic materials specific organic groups were enhanced. The prepared database of infrared transmission spectra included 23 dental materials, facilitating their appropriate identification. Application of infrared spectroscopy allowed for a quick differential identification of typical dental materials produced from organic compounds for inorganic restorations (porcelain) and of tooth structure-resembling hydroxyapatite and its contaminate forms with fluoride and carbonate ions.